C4-carboxylic acid-substituted tryptamine derivatives and methods of using

ABSTRACT

Disclosed are novel C4-carboxylic acid-substituted tryptamine derivative compounds and pharmaceutical and recreational drug formulations containing the same. The pharmaceutical formulations may be used to treat brain neurological disorders.

RELATED APPLICATIONS

This application is a continuation of Ser. No. 17/885,978, filed Aug. 11, 2022 which claims the benefit of United States Provisional U.S. Provisional Application No. 63/347,835 filed Jun. 1, 2022, and U.S. Provisional Application No. 63/321,440 filed Mar. 18, 2022; the entire contents of patent application Ser. Nos. 17/885,978; 63/347,835 and 63/321,440 are hereby incorporated by reference.

FIELD OF THE DISCLOSURE

The compositions and methods disclosed herein relate to a class of chemical compounds known as tryptamines. Furthermore, the compositions and methods disclosed herein relate to C₄-substituted tryptamine derivatives, and, in particular, to C₄-carboxylic acid-substituted tryptamine derivatives.

BACKGROUND OF THE DISCLOSURE

The following paragraphs are provided by way of background to the present disclosure. They are not however an admission that anything discussed therein is prior art or part of the knowledge of a person of skill in the art.

Tryptamines are a class of chemical compounds that share a common chemical structure (notably, a fused benzene and pyrrole ring, together known as an indole, and linked to the pyrrole ring, at the third carbon atom, a 2-aminoethyl group), and can be formulated as therapeutic drug compounds. For example, psilocybin has been evaluated as a drug for its clinical potential in the treatment of mental health conditions (Daniel, J. et al. Mental Health Clin., 2017; 7(1): 24-28), including to treat anxiety in terminal cancer patients (Grob, C. et al. Arch. Gen. Psychiatry, 2011, 68(1) 71-78) and to alleviate symptoms of treatment-resistant depression (Cathart-Harris, R. L. et al. Lancet Psychiatry, 2016, 3: 619-627). Other known drug compounds within the tryptamine class of compounds include, for example, melatonin, serotonin, bufotenin, dimethyltryptamine (DMT), and psilocin.

It is commonly understood that tryptamine-based drugs can produce their in vivo therapeutic effects by molecular interaction with macromolecules present in human cells, known as receptors. In this respect, in broad terms, specific receptors can be thought of as being located in a relatively fixed anatomical space (e.g., a specific brain tissue). Following administration of a drug, the drug moves through the body to the receptor to interact therewith, and then back out of the body. It is generally desirable that when a tryptamine-based drug is administered, the drug is specifically active at the desired anatomical location within a patient's body, such as, for example, in a specific brain tissue and/or at a specific receptor, a 5-hydroxytryptamine (5-HT) receptor, for example. Moreover, it is generally desirable that the specific molecular interaction between the drug and a receptor, such as a 5-HT receptor, is such that the drug-receptor molecular interaction results in appropriate modulation of the target receptor.

In many instances the observed pharmacological effect of tryptamine-based drugs is suboptimal. Thus, administration of the drug may fall short of the desired therapeutic effect (e.g., the successful treatment of a psychotic disorder) and/or undesirable side effects may be observed.

The underlying causes for these observed shortcomings in pharmacological effects may be manifold. For example, the administered drug additionally may interact with receptors other than the target receptor, and/or the specific molecular interaction between drug and target may not lead to the desired receptor modulation, and/or the concentration of the drug at the receptor may be suboptimal. In this respect, known tryptamine-based drugs can be said to frequently display suboptimal pharmacodynamic (PD) characteristics, i.e., suboptimal characteristics with respect to the pharmacological effect exerted by the drug on the body. Thus, for example, the intensity of the drug's effect, the concentration of the drug at the receptor, and the molecular interactions between the drug and receptor may not be as desired.

Furthermore, as is the case with many pharmaceutical compounds, tryptamine compounds when administered can penetrate multiple tissues by diffusion, resulting in broad bodily distribution of the drug compound (Bodor, N. et al., 2001, J. Pharmacy and Pharmacology, 53: 889-894). Thus, frequently a substantial proportion of the administered drug fails to reach the desired target receptor. This in turn may necessitate more frequent dosing of the drug. Such frequent dosing is less convenient to a patient, and, moreover, may negatively affect patient compliance with the prescribed drug therapy. In addition, generally toxicity associated with drug formulations tends to be more problematic as a result of broad bodily distribution of the drug throughout the patient's body since undesirable side effects may manifest themselves as a result of interaction of the drug with healthy organs.

Furthermore, it is generally desirable that drug compounds exert a pharmacological effect for an appropriate period of time. However, tryptamine-based drugs when systemically administered to a patient can exhibit a high blood plasma clearance, typically on the order of minutes (Vitale, A. et al., 2011, J. of Nucl. Med, 52(6), 970-977). Thus, rapid drug clearance can also necessitate more frequent dosing of tryptamine-based drug formulations. In this respect, known tryptamine containing drug formulations can be said to frequently display suboptimal pharmacokinetic (PK) characteristics, i.e., suboptimal characteristics with respect to movement of the drug through the body to and from the desired anatomical location, including, for example, suboptimal drug absorption, distribution, metabolism, and excretion.

There exists therefore a need in the art for improved tryptamine compounds.

SUMMARY OF THE DISCLOSURE

The following paragraphs are intended to introduce the reader to the more detailed description, not to define or limit the claimed subject matter of the present disclosure.

In one aspect, the present disclosure relates to tryptamines and derivative compounds thereof.

In another aspect, the present disclosure relates to C₄-substituted tryptamine derivative compounds.

In another aspect, the present disclosure relates to C₄-carboxylic acid-substituted tryptamine derivative compounds.

Accordingly, in one aspect, the present disclosure provides, in at least one embodiment, in accordance with the teachings herein, a chemical compound having chemical formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or a derivative thereof;         and     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group.

In at least one embodiment, in an aspect, the carboxylic acid moiety or derivative thereof can have the chemical formula (II):

-   -   wherein R_(4a) is an aryl group, a substituted aryl group, a         heteroaryl group, a substituted heteroaryl group, an alkyl         group, a substituted alkyl group, an amine group, or a         substituted amine group.

In at least one embodiment, in an aspect, the aryl group and substituted aryl group can be a phenyl group and a substituted phenyl group, respectively.

In at least one embodiment, in an aspect, the substituted aryl group can be a halo-substituted phenyl group.

In at least one embodiment, in an aspect, the alkyl group can be a C₁-C₁₀ alkyl group, in which optionally, at least one carbon atom in the alkyl chain is replaced with an oxygen (O) atom.

In at least one embodiment, in an aspect, the substituted alkyl group can be a C₁-C₁₀ alkyl group, wherein the optional substituents are at least one of halo, C₃-C₆ cycloalkyl, or amino (NH₂).

In at least one embodiment, in an aspect, the substituted alkyl group can be a C₁-C₁₀ alkyl group, wherein the optional substituent is C₃-C₆ cycloalkane.

In at least one embodiment, in an aspect, the substituted alkyl group can be a C₁-C₁₀ alkyl group, wherein the optional substituent is cyclo-propane.

In at least one embodiment, in an aspect, the substituted alkyl group can be —CH₂-cyclopropane.

In at least one embodiment, in an aspect, the aryl group can be a phenyl group in which two substituents on the phenyl group are joined together to form an additional 5-7-membered carbocyclic or heterocyclic ring.

In at least one embodiment, in an aspect, the 5-7-membered ring can be a methylene-dioxy ring, an ethylene-dioxy ring or a dihydrofuryl ring.

In at least one embodiment, in an aspect, the substituted aryl group can be an optionally substituted phenyl group which is substituted with an alkoxy group, a substituted alkoxy group, an acetamidyl group or an alkoxycarbonyl group.

In at least one embodiment, in an aspect, the alkoxycarbonyl group can be a methoxycarbonyl (CH₃OC(═O)—).

In at least one embodiment, in an aspect, the alkoxycarbonyl group can be a substituted heteroaryl-carbonyl group (heteroaryl-O—C(═O)—).

In at least one embodiment, in an aspect, the substituted phenyl group can be an O-alkylated phenyl group, in which the phenyl group can be substituted with one or more O-alkyl groups.

In at least one embodiment, in an aspect, the O-alkyl group can be a methoxy group, an ethoxy group, a propoxy group, an iso-propoxy group, or a butoxy group (n-but, s-but, or t-but).

In at least one embodiment, in an aspect, the O-alkylated phenyl group can be O-alkylated by one or more methoxy groups.

In at least one embodiment, in an aspect, the substituted phenyl group can be a halogenated phenyl group.

In at least one embodiment, in an aspect, the halogenated phenyl group can be a per-fluorinated phenyl.

In at least one embodiment, in an aspect, the substituted phenyl group can be a trifluoromethylated phenyl group (—CF₃), or a trifluoromethoxy phenyl group (—OCF₃).

In at least one embodiment, in an aspect, the substituted aryl group can be a substituted phenyl group having one or more substituents which are halo, alkoxy, alkyl, halo-substituted alkyl, or halo-substituted alkoxy.

In at least one embodiment, in an aspect, the phenyl group can be substituted with one or more of a trifluoromethoxy group, a methoxy group, or a halogen atom.

In at least one embodiment, in an aspect, R_(4a) can be a substituted pyridine group.

In at least one embodiment, in an aspect, the substituted pyridine group can be an O-alkylated pyridine group, an O-arylated pyridine group, or a halogenated pyridine group.

In at least one embodiment, in an aspect, the O-alkylated pyridine group can be O-alkylated by one or more methoxy groups.

In at least one embodiment, in an aspect, the O-alkylated pyridine group can be O-alkylated by one or more methoxy groups and one or more halogen atoms.

In at least one embodiment, in an aspect, the pyridine group can be substituted with a O-aryl group.

In at least one embodiment, in an aspect, the O-aryl group can be an O-phenyl group.

In at least one embodiment, in an aspect, the substituted aryl group can be a substituted phenyl group which is substituted by a carboxylate moiety.

In at least one embodiment, in an aspect, the substituted amine group can be —NH—CH₂R, where R is an organic radical.

In at least one embodiment, in an aspect, in the compound having chemical formula (I) the compound can be selected from the group consisting of C(I), C(II), C(III), C(IV), C(V), C(VI), C(VII), C(VIII), C(IX), C(X), C(XI), C(XII), C(XIII), C(XIV), C(XV), C(XVI), C(XVII), C(XVIII), C(XIX), C(XX), C(XXI), C(XXII), C(XXIII), C(XXIV), C(XXV), C(XXVI), C(XXVII), C(XXVIII), C(XXIX), C(XXX), C(XXXI), C(XXXII), C(XXXIII), C(XXXIV), C(XXXV), C(XXXVI), C(XXXVII), C(XXXVIII), C(XXXIX), C(XL), C(XLI), C(XLII), and C(XLIII):

In another aspect, the present disclosure relates to pharmaceutical and recreational drug formulations comprising C₄-carboxylic acid-substituted tryptamine derivative compounds. Accordingly, in one aspect, the present disclosure provides, in at least one embodiment, a pharmaceutical or recreational drug formulation comprising an effective amount of a chemical compound having a formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or derivative thereof,         and     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group, together with a         pharmaceutically acceptable excipient, diluent, or carrier.

In at least one embodiment, in an aspect, the pharmaceutical formulation can be a pro-drug pharmaceutical formulation, wherein the compound having formula (I) is in vivo hydrolyzed to form a compound having chemical formula (VI):

-   -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group.

In another aspect, the present disclosure relates to methods of treatment of brain neurological disorders. Accordingly, the present disclosure further provides, in one embodiment, a method for treating a brain neurological disorder, the method comprising administering to a subject in need thereof a pharmaceutical formulation comprising a chemical compound having a formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or derivative thereof,     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group, wherein the         pharmaceutical formulation is administered in an effective         amount to treat the brain neurological disorder in the subject.

In at least one embodiment, in an aspect, upon administration the compound having formula (I) can interact with a receptor in the subject to thereby modulate the receptor and exert a pharmacological effect.

In at least one embodiment, in an aspect, the receptor can be a 5-HT_(1A) receptor, a 5-HT_(2A) receptor, a 5-HT_(1B) receptor, a 5-HT_(2B) receptor, a 5-HT_(3A) receptor, an ADRA1A receptor, an ADRA2A receptor, a CHRM1 receptor, a CHRM2 receptor, a CNR1 receptor, a DRD1 receptor, a DRD2S receptor, or an OPRD1 receptor.

In at least one embodiment, in an aspect, upon administration the compound having formula (I) can interact with an enzyme or transmembrane transport protein in the subject to thereby modulate the enzyme or transmembrane transport protein and exert a pharmacological effect.

In at least one embodiment, in an aspect, the enzyme can be monoamine oxidase A (MOA-A), and the transmembrane transport protein can be a dopamine active transporter (DAT), a norephedrine transporter (NET), or a serotonin transporter (SERT) transmembrane transport protein.

In at least one embodiment, in an aspect, upon administration the compound having formula (I) can be in vivo hydrolyzed to form a compound having chemical formula (VI):

-   -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group,     -   and wherein the compound having chemical formula (VI) interacts         with a receptor to thereby modulate the receptor in the subject         and exert a pharmacological effect.

In at least one embodiment, in an aspect, the receptor can be 5-HT_(1A) receptor, a 5-HT_(2A) receptor, a 5-HT_(1B) receptor, a 5-HT_(2B) receptor, a 5-HT_(3A) receptor, an ADRA1A receptor, an ADRA2A receptor, a CHRM1 receptor, a CHRM2 receptor, a CNR1 receptor, a DRD1 receptor, a DRD2S receptor, or an OPRD1 receptor.

In at least one embodiment, in an aspect, the disorder can be a 5-HT_(1A) receptor-mediated disorder, a 5-HT_(2A) receptor-mediated disorder, a 5-HT_(1B) receptor-mediated disorder, a 5-HT_(2B) receptor-mediated disorder, a 5-HT_(3A) receptor-mediated disorder, an ADRA1A receptor-mediated disorder, an ADRA2A receptor-mediated disorder, a CHRM1 receptor-mediated disorder, a CHRM2 receptor-mediated disorder, a CNR1 receptor-mediated disorder, a DRD1 receptor-mediated disorder, a DRD2S receptor-mediated disorder, or an OPRD1 receptor-mediated disorder.

In at least one embodiment, in an aspect, a dose can be administered of about 0.001 mg to about 5,000 mg.

In another aspect, the present disclosure provides, in at least one embodiment, a method for modulating (i) a receptor selected from 5-HT_(1A) receptor, a 5-HT_(2A) receptor, a 5-HT_(1B) receptor, a 5-HT_(2B) receptor, a 5-HT_(3A) receptor, an ADRA1A receptor, an ADRA2A receptor, a CHRM1 receptor, a CHRM2 receptor, a CNR1 receptor, a DRD1 receptor, a DRD2S receptor, or an OPRD1 receptor; (ii) an enzyme, the enzyme being MOA-1; or (iii) a transmembrane transport protein selected from a dopamine active transporter (DAT), a norephedrine transporter (NET) or a serotonin transporter (SERT) transmembrane transport protein, the method comprising contacting (i) the 5-HT_(1A) receptor, the 5-HT_(2A) receptor, the 5-HT_(1B) receptor, the 5-HT_(2B) receptor, the 5-HT_(3A) receptor, the ADRA1A receptor, the ADRA2A receptor, the CHRM1 receptor, the CHRM2 receptor, the CNR1 receptor, the DRD1 receptor, the DRD2S receptor, or the OPRD1 receptor; (ii) MOA-1; or (iii) the dopamine active transporter (DAT), the norephedrine transporter (NET), or the serotonin transporter (SERT) transmembrane transport protein with a chemical compound having a formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or derivative thereof;         and     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group, under reaction         conditions sufficient to modulate (i) the 5-HT_(1A) receptor,         the 5-HT_(2A) receptor, the 5-HT_(1B) receptor, the 5-HT_(2B)         receptor, the 5-HT_(3A) receptor, the ADRA1A receptor, the         ADRA2A receptor, the CHRM1 receptor, the CHRM2 receptor, the         CNR1 receptor, the DRD1 receptor, the DRD2S receptor, or the         OPRD1 receptor; (ii) MOA-1; or (iii) the dopamine active         transporter (DAT), the norephedrine transporter (NET), or the         serotonin transporter (SERT) transmembrane transport protein.

In at least one embodiment, in an aspect, the reaction conditions can be in vitro reaction conditions.

In at least one embodiment, in an aspect, the reaction conditions can be in vivo reaction conditions.

In another aspect, the present disclosure relates to methods of making C₄-carboxylic acid-substituted tryptamine derivative compounds. Accordingly, disclosed herein are methods of making a chemical compound having chemical formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or a derivative thereof;         and     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group, wherein the method         involves the performance of at least one chemical synthesis         reaction selected from the reactions depicted in FIG. 3A (i), 3A         (ii), 4A, 5A, 6A, 7A, 8A, 9A, or 10A.

In at least one embodiment, in an aspect, the compound having chemical formula (I) can be a compound having formula C(V):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 3A (i) or, FIG. 3A (ii).

In at least one embodiment, in an aspect, the compound having chemical formula (I) can be a compound having formula C(VI):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 4A.

In at least one embodiment, in an aspect, the compound having chemical formula (I) can be a compound having formula C(VII):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 5A.

In at least one embodiment, in an aspect, the compound having chemical formula (I) can be a compound having formula C(III):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 6A.

In at least one embodiment, in an aspect, the compound having chemical formula (I) can be a compound having formula C(XLIII):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 7A.

In at least one embodiment, in an aspect, the compound having chemical formula (I) can be a compound having formula C(I):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 8A.

In at least one embodiment, in an aspect, the compound having chemical formula (I) can be a compound having formula C(XX):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 9A.

In at least one embodiment, in an aspect, the compound having chemical formula (I) can be a compound having formula C(IV):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 10A.

In another aspect, the present disclosure relates to uses of C₄-carboxylic acid-substituted tryptamine derivative compounds. Accordingly, the present disclosure further provides, in at least one embodiment, a use of a chemical compound having a formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or derivative thereof;     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group, in the manufacture of a         pharmaceutical or recreational drug formulation.

In at least one embodiment, the manufacture can comprise formulating the chemical compound with a pharmaceutically acceptable excipient, diluent, or carrier.

In another aspect the present disclosure provides, in at least one embodiment, a use of a chemical compound having a formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or derivative thereof;     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group, together with a         pharmaceutically acceptable diluent, carrier, or excipient as a         pharmaceutical or recreational drug formulation.

In at least one embodiment, in aspect, the pharmaceutical drug is a drug for the treatment of a brain neurological disorder.

Other features and advantages will become apparent from the following detailed description. It should be understood, however, that the detailed description, while indicating preferred implementations of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those of skill in the art from the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is in the hereinafter provided paragraphs described, by way of example, in relation to the attached figures. The figures provided herein are provided for a better understanding of the example embodiments and to show more clearly how the various embodiments may be carried into effect. The figures are not intended to limit the present disclosure.

FIG. 1 depicts the chemical structure of tryptamine.

FIG. 2 depicts a certain prototype structure of tryptamine and tryptamine derivative compounds, namely an indole. Certain carbon and nitrogen atoms may be referred to herein by reference to their position within the indole structure, i.e., N₁, C₂, C₃ etc. The pertinent atom numbering is shown.

FIGS. 3A (i), 3A (ii), 3B, 3C, 3D, 3E, 3F, 3G, 3H, 3I, 3J, 3K, 3L, 3M (i), 3M (ii), 3M (iii), 3N (i), 3N (ii), 3O (i), 3O (ii), 3O (iii), 3P, 3Q, 3R, 3S (i), and 3S (ii) depict an example chemical reaction to make an example chemical compound provided by the present disclosure, namely a compound having chemical formula C(V) (FIGS. 3A (i) and 3A (ii)) (the compound having chemical formula C(V) is referred to as compound (2) in FIGS. 3A (i) and 3A (ii)), and various graphs representing certain experimental results (FIGS. 3B-3S (ii)), notably graphs obtained in the performance experimental assays to evaluate the efficacy of an example compound a compound having chemical formula C(V), notably a cell viability assay (FIGS. 3B and 3C); a saturation binding assay for [³H]ketanserin at the 5-HT_(2A) receptor (FIG. 3D); a competition assay for psilocin as a positive control (binding) (FIG. 3E); a competition assay for psilocybin and tryptophan as a control and negative control (no binding), respectively (FIG. 3F); a competition assay for a compound with formula C(V), designated “C-V” (FIG. 3G); a cAMP assay in the presence of increasing forskolin concentrations in +5HT_(1A) cells and −5HT_(1A) cells (FIG. 3H); a cAMP assay in the presence of varying concentrations of tryptophan in +5HT_(1A) cells and −5HT_(1A) cells with 4 μM forskolin (FIG. 3I); a cAMP assay in the presence of varying concentrations of psilocin in +5HT_(1A) cells and −5HT_(1A) cells stimulated with 4 μM forskolin (FIG. 3J); a cAMP assay in the presence of varying concentrations of serotonin in +5HT_(1A) cells and −5HT_(1A) cells stimulated with 4 μM forskolin (FIG. 3K); a cAMP assay in the presence of varying concentrations of the compound having chemical formula C(V), designated “C-V” in +5HT_(1A) cells and −5HT_(1A) cells with 4 μM forskolin (FIG. 3L); psilocybin metabolic conversion assays (FIGS. 3M (i)-3M (iii)); assay controls for psilocin metabolic release assays (FIGS. 3N (i)-3N (ii)); metabolic stability assays for a compound with formula C(V) (FIGS. 3O (i)-3O (iii)); and drug-induced Head Twitch Response (HTR) assays using the compound having formula C(V), designated “C-V” (FIG. 3P); mouse PK studies analyzing plasma psilocybin levels after 1 mg/kg i.v. dose of psilocybin (FIG. 3Q); mouse PK studies analyzing plasma psilocin levels after oral dosing of various levels of psilocybin. (FIG. 3R): and mouse PK studies using a chemical compound having formula C(V) (FIGS. 3S (i) and 3S (ii)).

FIGS. 4A, 4B, 4C, 4D, 4E, 4F (i), 4F(ii), 4F (iii), 4G, FIGS. 4H (i), and 4H (ii) depict an example chemical reaction to make an example chemical compound provided by the present disclosure, namely a compound having chemical formula C(VI), (FIG. 4A) (the compound having chemical formula C(VI) is referred to as compound (3) in FIG. 4A), and various graphs representing certain experimental results (FIGS. 4B-4H (ii)), notably graphs obtained in the performance experimental assays to evaluate the efficacy of an example compound a compound having chemical formula C(VI), notably a cell viability assay (FIGS. 4B and 4C); a competition assay for a compound with formula C(VI), designated “C-VI” (FIG. 4D); a cAMP assay in the presence of varying concentrations of the compound having chemical formula C(VI), designated “C-VI” in +5HT_(1A) cells and −5HT_(1A) cells with 4 μM forskolin (FIG. 4E); metabolic stability assays and assays to evaluate the capacity of assayed molecules to release psilocin under various in vitro conditions (FIGS. 4F (i)-4F (iii)); Drug-induced Head Twitch Response (HTR) assays using the compound having formula C(VI), designated “C-VI” (FIG. 4G); and mouse PK studies using a chemical compound having formula C(VI) (FIGS. 4H (i) and 4H (ii)).

FIGS. 5A, 5B, 5C, 5D, 5E (i), 5E (ii), and 5F depict an example chemical reaction to make an example chemical compound provided by the present disclosure, namely a compound having chemical formula C(VII) (FIG. 5A) (the compound having chemical formula C(VII) is referred to as compound (4) in FIG. 5A), and various graphs representing certain experimental results (FIGS. 5B-5F (ii)), notably, graphs obtained in the performance experimental assays to evaluate the efficacy of an example compound a compound having chemical formula C(VII), notably a cell viability assay (FIG. 5B); a competition assay for a compound with formula C(VII), designated “C-VII” (FIG. 5C); a cAMP assay in the presence of varying concentrations of the compound having chemical formula C(VII), designated “C-VII” in +5HT_(1A) cells and −5HT_(1A) cells with 4 μM forskolin (FIG. 5D); metabolic stability assays for compound with formula C(VII), designated “C-VII”; (FIGS. 5E (i) and 5E (ii)); and Drug-induced Head Twitch Response (HTR) assays using the compound having formula C(VII), designated “C-VII” (FIG. 5F).

FIGS. 6A, 6B, 6C, 6D, 6E, 6F (i), 6F (ii), and 6G depict an example chemical reaction to make an example chemical compound provided by the present disclosure, namely a compound having chemical formula C(III) (FIG. 6A) (the compound having chemical formula C(III) is referred to as compound (11) in FIG. 6A), and various graphs representing certain experimental results (FIGS. 6B-6G), notably graphs obtained in the performance experimental assays to evaluate the efficacy of an example compound a compound having chemical formula C(III), notably a cell viability assay (FIGS. 6B and 6C); a competition assay for a compound with formula C(III), designated “C-III” (FIG. 6D); a cAMP assay in the presence of varying concentrations of the compound having chemical formula C(III), designated “C-III” in +5HT_(1A) cells and −5HT_(1A) cells with 4 μM forskolin (FIG. 6E); metabolic stability assays and assays to evaluate the capacity of assayed molecules to release psilocin under various in vitro conditions (FIGS. 6F (i)-6F (ii)); and Drug-induced Head Twitch Response (HTR) assays using the compound having formula C(III), designated “C-III” (FIG. 6G);

FIGS. 7A, 7B, 7C, 7D, 7E, 7F (i), and 7F (ii), depict an example chemical reaction to make an example chemical compound provided by the present disclosure, namely a compound having chemical formula C(XLIII), (FIG. 7A) (the compound having chemical formula C(XLIII) is referred to as compound (13) in FIG. 7A), and various graphs representing certain experimental results (FIGS. 7B-7F (ii)), notably graphs obtained in the performance experimental assays to evaluate the efficacy of an example compound a compound having chemical formula C(XLIII), notably a cell viability assay (FIGS. 7B and 7C); a competition assay for a compound with formula C(XLIII), designated “C-XLIII” (FIG. 7D); a cAMP assay in the presence of varying concentrations of the compound having chemical formula C(XLIII), designated “C-XLIII” in +5HT_(1A) cells and −5HT_(1A) cells with 4 μM forskolin (FIG. 7E); and metabolic stability assays and assays to evaluate the capacity of assayed molecules to release psilocin under various in vitro conditions (FIGS. 7F (i)-7F (ii).

FIGS. 8A, 8B, 8C, 8D, 8E, 8F (i), 8F (ii), 8G, 8H, 8I (i), and 8I (ii) depict an example series of chemical reactions to make an example chemical compound provided by the present disclosure, namely a compound having chemical formula C(I) (FIG. 8A) (the compound having chemical formula C(I) is referred to as compound (8) in FIG. 8A), and various graphs representing certain experimental results (FIGS. 8B-8I (ii)), notably graphs obtained in the performance experimental assays to evaluate the efficacy of an example compound a compound having chemical formula C(I), notably a cell viability assay (FIGS. 8B and 8C); a competition assay for a compound with formula C(I), designated “C-I” (FIG. 8D); a cAMP assay in the presence of varying concentrations of the compound having chemical formula C(I), designated “C-I” in +5HT_(1A) cells and −5HT_(1A) cells with 4 μM forskolin (FIG. 8E); metabolic stability assays and assays to evaluate the capacity of assayed molecules to release psilocin under various in vitro conditions (FIGS. 8F (i)-8F (ii)); Drug-induced Head Twitch Response (HTR) assays using the compound having formula C(I), designated “C-I” (FIG. 8G); mouse PK studies using a chemical compound having formula C(I) administered in various amounts and using various administration modalities (FIG. 8H); and mouse PK studies using a chemical compound having formula C(I) (FIGS. 8I (i) and 8I (ii)).

FIGS. 9A, 9B, 9C, 9D, 9E, 9F (i), 9F (ii), 9G, 9H, 9I (i), and 9I (ii) depict an example chemical reaction to make an example chemical compound provided by the present disclosure, namely a compound having chemical formula C(XX) (FIG. 9A) (the compound having chemical formula C(XX) is referred to as compound (2) in FIG. 9A), and various graphs representing certain experimental results (FIGS. 9B-9I (ii)), notably graphs obtained in the performance experimental assays to evaluate the efficacy of an example compound a compound having chemical formula C(XX), notably a cell viability assay (FIGS. 9B and 9C); a competition assay for a compound with formula C(XX), designated “C-XX” (FIG. 9D); a cAMP assay in the presence of varying concentrations of the compound having chemical formula C(XX), designated “C-XX” in +5HT_(1A) cells and −5HT_(1A) cells with 4 μM forskolin (FIG. 9E); metabolic stability assays and assays to evaluate the capacity of assayed molecules to release psilocin under various in vitro conditions (FIGS. 9F (i)-9F (ii)); Drug-induced Head Twitch Response (HTR) assays using the compound having formula C(XX), designated “C-XX” (FIG. 9G); mouse PK studies using a chemical compound having formula C(XX) administered in various amounts and using various administration modalities (FIG. 9H); and mouse PK studies using a chemical compound having formula C(XX) (FIGS. 9I (i) and 9I (ii)).

FIGS. 10A, 10B, 10C, 10D, 10E, 10F (i), 10F (ii), 10G, 10H (i), and 10H (ii) depict an example chemical reaction to make an example chemical compound provided by the present disclosure, namely a compound having chemical formula C(IV), (FIG. 10A) (the compound having chemical formula C(IV) is referred to as compound (2) in FIG. 10A), and various graphs representing certain experimental results (FIGS. 10B-10H (ii)), notably graphs obtained in the performance experimental assays to evaluate the efficacy of an example compound a compound having chemical formula C(IV), notably a cell viability assay (FIGS. 10B and 10C); a competition assay for a compound with formula C(IV), designated “C-IV” (FIG. 10D); a cAMP assay in the presence of varying concentrations of the compound having chemical formula C(IV), designated “C-IV” in +5HT_(1A) cells and −5HT_(1A) cells with 4 μM forskolin (FIG. 10E); metabolic stability assays and assays to evaluate the capacity of assayed molecules to release psilocin under various in vitro conditions (FIGS. 10F (i)-10F (ii)); Drug-induced Head Twitch Response (HTR) assays using the compound having formula C(IV), designated “C-IV” (FIG. 10G), and mouse PK studies using a chemical compound having formula C(IV) (FIGS. 10H (i) and 10H (ii)).

The figures together with the following detailed description make apparent to those skilled in the art how the disclosure may be implemented in practice.

DETAILED DESCRIPTION

Various compositions, systems or processes will be described below to provide an example of an embodiment of each claimed subject matter. No embodiment described below limits any claimed subject matter and any claimed subject matter may cover processes, compositions or systems that differ from those described below. The claimed subject matter is not limited to compositions, processes or systems having all of the features of any one composition, system or process described below or to features common to multiple or all of the compositions, systems or processes described below. It is possible that a composition, system, or process described below is not an embodiment of any claimed subject matter. Any subject matter disclosed in a composition, system or process described below that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicant(s), inventor(s) or owner(s) do not intend to abandon, disclaim or dedicate to the public any such subject matter by its disclosure in this document.

As used herein and in the claims, the singular forms, such “a”, “an” and “the” include the plural reference and vice versa unless the context clearly indicates otherwise. Throughout this specification, unless otherwise indicated, “comprise,” “comprises” and “comprising” are used inclusively rather than exclusively, so that a stated integer or group of integers may include one or more other non-stated integers or groups of integers.

Various compositions, systems or processes will be described below to provide an example of an embodiment of each claimed subject matter. No embodiment described below limits any claimed subject matter and any claimed subject matter may cover processes, compositions or systems that differ from those described below. The claimed subject matter is not limited to compositions, processes or systems having all of the features of any one composition, system or process described below or to features common to multiple or all of the compositions, systems or processes described below. It is possible that a composition, system, or process described below is not an embodiment of any claimed subject matter. Any subject matter disclosed in a composition, system or process described below that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicant(s), inventor(s) or owner(s) do not intend to abandon, disclaim or dedicate to the public any such subject matter by its disclosure in this document.

When ranges are used herein for physical properties, such as molecular weight, or chemical properties, such as chemical formulae, all combinations and sub-combinations of ranges and specific embodiments therein are intended to be included. Other than in the operating examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein should be understood as modified in all instances by the term “about.” The term “about” when referring to a number or a numerical range means that the number or numerical range referred to is an approximation within experimental variability (or within statistical experimental error), and thus the number or numerical range may vary between 1% and 15% of the stated number or numerical range, as will be readily recognized by context. Furthermore, any range of values described herein is intended to specifically include the limiting values of the range, and any intermediate value or sub-range within the given range, and all such intermediate values and sub-ranges are individually and specifically disclosed (e.g., a range of 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.90, 4, and 5). Similarly, other terms of degree such as “substantially” and “approximately” as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed as including a deviation of the modified term if this deviation would not negate the meaning of the term it modifies.

Unless otherwise defined, scientific and technical terms used in connection with the formulations described herein shall have the meanings that are commonly understood by those of ordinary skill in the art. The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention, which is defined solely by the claims.

All publications, patents and patent applications are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference in its entirety.

Terms and Definitions

The term “tryptamine” refers to a chemical compound having the structure set forth in FIG. 1 .

The term “indole prototype structure” refers to the chemical structure shown in FIG. 2 . It is noted that specific carbon atoms and a nitrogen atom in the indole prototype structure are numbered. Reference may be made to these carbon and nitrogen numbers herein, for example C₂, C₄, N₁, and so forth. Furthermore, reference may be made to chemical groups attached to the indole prototype structure in accordance with the same numbering, for example, R₄ and R₆ reference chemical groups attached to the C₄ and C₆ atom, respectively. In addition, R_(3a) and R_(3b), in this respect, reference chemical groups extending from the ethyl-amino group extending in turn from the C₃ atom of the prototype indole structure.

The term “tryptamine derivative”, as used herein, refers to compounds that can be derivatized from tryptamine, wherein such compounds include an indole prototype structure and a C₃ ethylamine or ethylamine derivative group having the formula (VII):

-   -   wherein R₄, is a substituent (any atom or group other than a         hydrogen atom) comprising a carboxylic acid moiety or a         derivative thereof, and wherein R_(3a) and R_(3b) are each         independently a hydrogen atom, an alkyl group, or an aryl group.         Thus, tryptamine derivative compounds include compounds         containing a substituent at C₄, as defined. Additional other         atoms, such as N₁, may also be substituted. Moreover, in this         respect, tryptamine derivatives containing a substituent atom or         group at e.g., C₄ may be referred to as C₄-substituted         tryptamine derivatives. In chemical formula (VII), R₄, can, for         example, be a carboxylic acid moiety or derivative thereof, and         the tryptamine derivative may be referred to as a C₄-carboxylic         acid-substituted tryptamine derivative.

The terms “carboxyl group”, “carboxyl”, “carboxylic acid” and “carboxy”, as used herein, refer to a molecule containing one atom of carbon bonded to an oxygen atom and a hydroxy group and having the formula —COOH. A carboxyl group includes a deprotonated carboxyl group, i.e., a carboxyl ion, having the formula —COO—. In its deprotonated form a carboxyl group may form a carboxyl salt, for example, a sodium or potassium carboxyl salt, or an organic carboxyl salt.

The term “carboxylic acid moiety or derivative thereof”, as used herein, refers to a modulated carboxyl group wherein the hydroxy group of the carboxyl group has been substituted by another atom or group. Thus, a carboxylic acid moiety or derivative thereof includes a group having chemical formula (X):

-   -   wherein, wherein R₄′, for example, is an aryl group, a         substituted aryl group, a heteroaryl group, a substituted         heteroaryl group, an alkyl group, a substituted alkyl group, an         amine group, or a substituted amine group. It is noted that the         partially bonded oxygen atom of the group having formula (X) can         be bonded to another entity, including, for example, to the C₄         atom of tryptamine.

The terms “halogen”, “halogenated” and “halo-”, as used herein, refer to the class of chemical elements consisting of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I). Accordingly, halogenated compounds can refer to “fluorinated”, “chlorinated”, “brominated”, or “iodinated” compounds.

The terms “hydroxy group”, and “hydroxy”, as used herein, refers to a molecule containing one atom of oxygen bonded to one atom of hydrogen and having the formula —OH. A hydroxy group through its oxygen atom may be chemically bonded to another entity.

The term “amino group” and “amino”, as used herein, refers to a molecule containing one atom of nitrogen bonded to hydrogen atoms and having the formula —NH₂. An amino group also may be protonated and having the formula —NH₃ ⁺.

The term “alkyl group”, as used herein, refers to a straight and/or branched chain, saturated alkyl radical containing from one to “p” carbon atoms (“C1-Cp-alkyl”) and includes, depending on the identity of “p”, methyl, ethyl, propyl, isopropyl, n-butyl, s-butyl, isobutyl, t-butyl, 2,2-dimethylbutyl, n-pentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl, n-hexyl, and the like, where the variable p is an integer representing the largest number of carbon atoms in the alkyl radical. Alkyl groups further include hydrocarbon groups arranged in a chain having the chemical formula —CnH2n+1, including, without limitation, methyl groups (—CH3), ethyl groups (—C2H5), propyl groups (—C3H7), and butyl groups (—C4H9).

The term “alkylene”, as used herein, refers to a divalent alkyl.

The term “cyclo-alkyl”, as used herein, refers to cyclo-alkyl groups, including (C₃-C₂₀), (C₃-C₁₀), and (C₃-C₆) cyclo-alkyl groups, and includes saturated and partially saturated cyclo-alkyl groups, further including cyclo-propane, cyclo-butane, cyclo-pentane, cyclo-hexane, cyclo-heptane, cyclopentene and cyclohexene.

The terms “O-alkyl group”, and “alkoxy group”, as used herein interchangeably, refer to a hydrocarbon group arranged in a chain having the chemical formula —O—C_(n)H_(2n+1). O-alkyl groups include, without limitation, O-methyl groups (—O—CH₃) (i.e., methoxy), O-ethyl groups (—O—C₂H₅) (i.e., ethoxy), O-propyl groups (—O—C₃H₇) (i.e., propoxy) and O-butyl groups (—O—C₄H₉) (i.e., butoxy).

The term “aryl group”, as used herein, refers to a hydrocarbon group arranged in an aromatic ring and can, for example, be a C₆-C₁₄-aryl, a C₆-C₁₀-aryl. Aryl groups further include phenyl, naphthyl, tetrahydronaphthyl, phenanthrenyl, biphenylenyl, indanyl, tolyl, xylyl, or indenyl groups, and the like.

The term “hetero”, as used herein (e.g., “heterocycle”, “heteroaryl”, “alkyl-heteroaryl”), means a saturated or partially saturated or aromatic cyclic group, in which one or two ring atoms are a heteroatom selected from N, O, or S, the remaining ring atoms being C. Included are, for example, (C₃-C₂₀), (C₃-C₁₀), and (C₃-C₆) cyclic groups comprising one or two hetero atoms selected from O, S, or N. Furthermore, the saturated, unsaturated, or aromatic cyclic group can be optionally fused to an aryl or heteroaryl ring, or to a cyclo-alkyl ring.

The term “alcohol group” or “hydroxylalkyl”, as used herein, refers to a hydrocarbon group arranged in a chain having the chemical formula C_(n)H_(n+1)OH. Depending on the carbon chain, length specific alcohol groups may be termed a methanol group (n=1) or hydroxymethyl, an ethanol group (n=2) or hydroxyethyl, a propanol group (n=3) or hydroxypropyl, a butanol group (n=4) or hydroxybutyl etc.

The term “receptor”, as used herein, refers to a protein present on the surface of a cell, or in a cell not associated with a cellular surface (e.g., a soluble receptor) capable of mediating signaling to and/or from the cell, or within the cell and thereby affect cellular physiology. Example receptors include, 5-HT_(1A) receptors, 5-HT_(1B) receptors, 5-HT_(2A) receptors, and “5-HT_(2B) receptors”, and so on. In this respect, “signaling” refers to a response in the form of a series of chemical reactions which can occur when a molecule, including, for example, the C₄-substituted tryptamine derivatives disclosed herein, interacts with a receptor. Signaling generally proceeds across a cellular membrane and/or within a cell, to reach a target molecule or chemical reaction, and results in a modulation in cellular physiology. Thus, signaling can be thought of as a transduction process by which a molecule interacting with a receptor can modulate cellular physiology, and, furthermore, signaling can be a process by which molecules inside a cell can be modulated by molecules outside a cell. Signaling and interactions between molecules and receptors, including for example, affinity, binding efficiency, and kinetics, can be evaluated through a variety of assays, including, for example, assays known as receptor binding assays (for example, radioligand binding assays, such as e.g., [³H]ketanserin assays may be used to evaluate receptor 5-HT_(2A) receptor activity), competition assays, and saturation binding assays, and the like.

The term “5-HT_(1A) receptor”, as used herein, refers to a subclass of a family of receptors for the neurotransmitter and peripheral signal mediator serotonin. 5-HT_(1A) receptors can mediate a plurality of central and peripheral physiologic functions of serotonin. Ligand activity at 5-HT_(1A) is generally not associated with hallucination, although many hallucinogenic compounds are known to modulate 5-HT_(1A) receptors to impart physiological responses (Inserra et al., 2020, Pharmacol. Rev 73: 202). 5-HT_(1A) receptors are implicated in various brain neurological disorders, including depression and anxiety, schizophrenia, and Parkinson's disease (Behav. Pharm. 2015, 26:45-58).

The term “5-HT_(1B) receptor”, as used herein, refers to a subclass of a family of receptors for the neurotransmitter and peripheral signal mediator serotonin. 5-HT_(1B) receptors can mediate a plurality of central and peripheral physiologic functions of serotonin. Ligand activity at 5-HT_(1B) is generally not associated with hallucination, although many hallucinogenic compounds are known to modulate 5-HT_(1A) receptors to impart physiological responses (Inserra et al., 2020, Pharmacol. Rev. 73: 202). 5-HT_(1B) receptors are implicated in various brain neurological disorders, including depression (Curr. Pharm. Des. 2018, 24:2541-2548).

The term “5-HT_(2A) receptor”, as used herein, refers to a subclass of a family of receptors for the neurotransmitter and peripheral signal mediator serotonin. 5-HT_(2A) receptors can mediate a plurality of central and peripheral physiologic functions of serotonin. Central nervous system effects can include mediation of hallucinogenic effects of hallucinogenic compounds. 5-HT_(2A) receptors are implicated in various brain neurological disorders (Nat. Rev. Drug Discov. 2022, 21:463-473; Science 2022, 375:403-411).

The term “5-HT_(2B) receptor”, as used herein, refers to a subclass of a family of receptors for the neurotransmitter and peripheral signal mediator serotonin. 5-HT_(2B) receptors can mediate a plurality of central and peripheral physiologic functions of serotonin. Central nervous system effects can include mediation of hallucinogenic effects of hallucinogenic compounds. 5-HT_(bA) receptors are implicated in various brain neurological disorders, including schizophrenia (Pharmacol. Ther. 2018, 181:143-155) and migraine (Cephalalgia 2017, 37:365-371).

The term “5-HT_(3A) receptor”, as used herein, refers to a subclass of a family of receptors for the neurotransmitter and peripheral signal mediator serotonin. 5-HT_(3A) receptors can mediate a plurality of central and peripheral physiologic functions of serotonin. 5-HT_(3A) receptors are implicated in various brain neurological disorders, including depression (Expert Rev. Neurother. 2016, 16:483-95).

The term “ADRA1A receptor”, as used herein, refers to a subclass of a family of receptors, also known as α1-adrenergic receptors, which can be modulated by selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressant (TCA) (Int. J. Mol Sci. 2021, 22: 4817; Brain Res. 1285 2009, 148-157). ADRA1A receptors are implicated in various brain neurological disorders, including depression.

The term “ADRA2A receptor”, as used herein, refers to a subclass of a family of receptors, also known as α2-adrenergic receptors. ADRA2A receptors are implicated in various brain neurological disorders, including Attention Deficit Hyperactivity Disorder (ADHD) (J. Am. Acad. Child. Adolesc. Psychiatry 2014, 53:153-73), mania, bipolar disorder, and schizophrenia.

The term “CHRM1 receptor”, as used herein, refers to a subclass of receptors also known as “cholinergic receptor muscarinic 1”, which can be modulated by selective serotonin reuptake inhibitors (SSRIs) (e.g., paroxetine) and tricyclic antidepressant (TCA). The class of CHRM receptors are implicated in various brain neurological disorders, including depression, major depression disorder (MDD), and bipolar disorder (Mol. Psychiatry 2019, 24: 694-709).

The term “CHRM2 receptor”, as used herein, refers to a subclass of receptors also known as “cholinergic receptor muscarinic 2”, which can be modulated by tricyclic antidepressant (TCA). The class of CHRM receptors are implicated in various brain neurological disorders, including depression, major depression disorder (MDD), and bipolar disorder (Mol. Psychiatry 2019, 24: 694-709).

The term “CNR1 receptor”, as used herein, refers to a subclass of receptors also known as “cannabinoid receptor CB₁”, which can be modulated by cannabinoid compounds. CNR receptors are implicated in various brain neurological disorders, including depression and schizophrenia (Pharmacol. Res. 2021, 170: 105729).

The term “DRD1 receptor”, as used herein, refers to a subclass of receptors also known as “dopamine receptor D₁”, which can be modulated by dopamine. Dopamine receptors are implicated in various brain neurological disorders, including schizophrenia, psychosis, and depression (Neurosci. Lett. 2019, 691:26-34).

The term “DRD2S receptor”, as used herein, refers to a subclass of receptors also known as “dopamine receptor D₂S”, which can be modulated by dopamine. Dopamine receptors are implicated in various brain neurological disorders, including schizophrenia, psychosis, and depression (Neurosci. Lett. 2019, 691:26-34).

The term “OPRD1 receptor”, as used herein, refers to a subclass of receptors also known as “opioid receptor D₁”, which can be modulated by opioid compounds. OPRD1 receptors are implicated in various brain neurological disorders, including psychopathy, and substance abused disorder (Mol. Psychiatry 2020, 25:3432-3441).

The term “MAO-A”, as used herein, refers to an enzyme involved in signaling also known as “Monoamine oxygenase A”, which can catalyze reactions which modulate signaling molecules, notably, for example, the deamination of the signaling molecules dopamine, norepinephrine, and serotonin. Compounds capable of modulating MOA, e.g., inhibitors of MOA, may be used to treat various brain neurological disorders, including panic disorders, depression, and Parkinson's disease (J. Clin. Psychiatry 2012, 73 Suppl. 1:37-41).

The term “DAT”, as used herein, refers to a transmembrane transport protein also known as “dopamine active transporter”, which is involved of transporting dopamine into the cytosol. DAT is implicated in various brain neurological disorders, notably dopamine related disorders such as attention deficit hyperactivity disorder (ADHD), bipolar disorder, and clinical depression, anxiety (Am. J. Med. Genet. B Neuropsychiatr. Genet. 2018, 177:211-231).

The term “NET”, as used herein, refers to a transmembrane transport protein also known as “norepinephrine transporter” or “noradrenaline transporter” or “NAT” which is involved in Na⁺/Cl⁻ dependent re-uptake of extracellular norepinephrine or noradrenaline. NET is implicated in various brain neurological disorders, including attention deficit hyperactivity disorder (ADHD) and clinical depression (Neurosci. Biobehav. Rev, 2013, 37:1786-800).

The term “SERT”, as used herein, refers to a transmembrane transport protein also known as “serotonin transporter” which is involved in neuronal serotonin transport, notably from the synaptic cleft back to the presynaptic neuron, thereby terminating the action of serotonin. SERT is implicated in various brain neurological disorders, including anxiety and depression (Pharmacol. Rep. 2018, 70:37-46).

The term “modulating receptors”, as used herein, refers to the ability of a compound disclosed herein to alter the function of receptors. A receptor modulator may activate the activity of a receptor, or inhibit the activity of a receptor depending on the concentration of the compound exposed to the receptor. Such activation or inhibition may be contingent on the occurrence of a specific event, such as activation of a signal transduction pathway, and/or maybe manifest only in particular cell types. The term “modulating receptors,” also refers to altering the function of a receptor by increasing or decreasing the probability that a complex forms between a receptor and a natural binding partner to form a multimer. A receptor modulator may increase the probability that such a complex forms between the receptor and the natural binding partner, may increase or decrease the probability that a complex forms between the receptor and the natural binding partner depending on the concentration of the compound exposed to the receptor, and or may decrease the probability that a complex forms between the receptor and the natural binding partner. It is further noted that the C₄-carboxylic acid-substituted tryptamine derivatives of the present disclosure may alter the function of a receptor by acting as an agonist or antagonist of the receptor, and that C₄-carboxylic acid-substituted tryptamine derivatives according to the present disclosure may alter the function of a receptor by directly interacting therewith or binding thereto, or by indirectly interacting therewith through one or more other molecular entities. In general, the receptor may be any receptor, including any receptor set forth herein, such as any of a 5-HT_(1A), 5-HT_(1B), 5-HT_(2A), a 5-HT_(2B), 5-HT_(3A), ADRA1A, ADRA2A, CHRM1, CHRM2, CNR1, DRD1, DRD2S, or OPRD1 receptor, for example. Accordingly, it will be clear, that in order to refer modulating specific receptors, terms such as “modulating 5-HT_(1A) receptors”, “modulating 5-HT_(1B) receptors”, “modulating 5-HT_(2A) receptors”, “modulating 5-HT_(2B) receptors”, and so forth, may be used herein.

The term “receptor-mediated disorder”, as used herein, refers to a disorder that is characterized by abnormal receptor activity. A receptor-mediated disorder may be completely or partially mediated by modulating a receptor. In particular, a receptor-mediated disorder is one in which modulation of the receptor results in some effect on an underlying disorder e.g., administration of a receptor modulator results in some improvement in at least some of the subjects being treated. In general, the receptor may be any receptor, including any receptor set forth herein, such as any of a 5-HT_(1A), 5-HT_(1B), 5-HT_(2A), a 5-HT_(2B), 5-HT_(3A), ADRA1A, ADRA2A, CHRM1, CHRM2, CNR1, DRD1, DRD2S, or OPRD1 receptor, for example. Accordingly, it will be clear, that in order to refer specific receptor-mediated disorders, terms such as “5-HT_(1A) receptor-mediated disorder”, “5-HT_(1B) receptor-mediated disorder”, “5-HT_(2A) receptor-mediated disorder”, “5-HT_(2B) receptor-mediated disorder”, and so forth, may be used.

The term “pharmaceutical formulation”, as used herein, refers to a preparation in a form which allows an active ingredient, including a psychoactive ingredient, contained therein to provide effective treatment, and which does not contain any other ingredients which cause excessive toxicity, an allergic response, irritation, or other adverse response commensurate with a reasonable risk/benefit ratio. The pharmaceutical formulation may contain other pharmaceutical ingredients such as excipients, carriers, diluents, or auxiliary agents.

The term “recreational drug formulation”, as used herein, refers to a preparation in a form which allows a psychoactive ingredient contained therein to be effective for administration as a recreational drug, and which does not contain any other ingredients which cause excessive toxicity, an allergic response, irritation, or other adverse response commensurate with a reasonable risk/benefit ratio. The recreational drug formulation may contain other ingredients such as excipients, carriers, diluents, or auxiliary agents.

The term “effective for administration as a recreational drug”, as used herein, refers to a preparation in a form which allows a subject to voluntarily induce a psychoactive effect for non-medical purposes upon administration, generally in the form of self-administration. The effect may include an altered state of consciousness, satisfaction, pleasure, euphoria, perceptual distortion, or hallucination.

The term “effective amount”, as used herein, refers to an amount of an active agent, pharmaceutical formulation, or recreational drug formulation, sufficient to induce a desired biological or therapeutic effect, including a prophylactic effect, and further including a psychoactive effect. Such effect can include an effect with respect to the signs, symptoms or causes of a disorder, or disease or any other desired alteration of a biological system. The effective amount can vary depending, for example, on the health condition, injury stage, disorder stage, or disease stage, weight, or sex of a subject being treated, timing of the administration, manner of the administration, age of the subject, and the like, all of which can be determined by those of skill in the art.

The terms “treating” and “treatment”, and the like, as used herein, are intended to mean obtaining a desirable physiological, pharmacological, or biological effect, and includes prophylactic and therapeutic treatment. The effect may result in the inhibition, attenuation, amelioration, or reversal of a sign, symptom or cause of a disorder, or disease, attributable to the disorder, or disease, which includes mental and psychiatric diseases and disorders. Clinical evidence of the prevention or treatment may vary with the disorder, or disease, the subject, and the selected treatment.

The term “pharmaceutically acceptable”, as used herein, refers to materials, including excipients, carriers, diluents, or auxiliary agents, that are compatible with other materials in a pharmaceutical or recreational drug formulation and within the scope of reasonable medical judgement suitable for use in contact with a subject without excessive toxicity, allergic response, irritation, or other adverse response commensurate with a reasonable risk/benefit ratio.

The terms “substantially pure” and “isolated”, as may be used interchangeably herein describe a compound, e.g., a C₄-carboxylic acid-substituted tryptamine derivative, which has been separated from components that naturally or synthetically accompany it. Typically, a compound is substantially pure when at least 60%, more preferably at least 75%, more preferably at least 90%, 95%, 96%, 97%, or 98%, and most preferably at least 99% of the total material (by volume, by wet or dry weight, or by mole percent or mole fraction) in a sample is the compound of interest. Purity can be measured by any appropriate method, e.g., by chromatography, gel electrophoresis or HPLC analysis.

General Implementation

As hereinbefore mentioned, the present disclosure relates to tryptamine derivatives. In particular, the present disclosure provides novel C₄-substituted tryptamine derivatives, and in particular to C₄-carboxylic acid-substituted tryptamine derivatives. In general, the herein provided compositions exhibit functional properties which deviate from the functional properties o tryptamine. Thus, for example, the C₄-carboxylic acid-substituted tryptamine derivatives can exhibit pharmacological properties which deviate from tryptamine. Furthermore, the C₄-carboxylic acid-substituted tryptamine derivatives may exhibit physico-chemical properties which differ from tryptamine. Thus, for example, C₄-carboxylic acid-substituted tryptamine derivatives may exhibit superior solubility in a solvent, for example, an aqueous solvent. Furthermore, the C₄-carboxylic acid-substituted tryptamine derivatives may exhibit pharmacokinetics or pharmacodynamics which are different from a non-substituted compound. The C₄-carboxylic acid-substituted tryptamine derivatives in this respect are useful in the formulation of pharmaceutical or recreational drug formulations.

In what follows selected embodiments are described with reference to the drawings.

Accordingly, in one aspect, the present disclosure provides derivatives of a compound known as tryptamine of which the chemical structure is shown in FIG. 1 . The derivatives herein provided are, in particular, C₄-substituted tryptamine derivatives, i.e., derivatives, wherein the C₄ atom is bonded to a substituent group, notably a carboxylic acid moiety or derivative thereof.

Thus, in one aspect, the present disclosure provides, in accordance with the teachings herein, in at least one embodiment, a compound having chemical formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or derivative thereof;     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group.

Thus, referring to the chemical compound having the formula (I), in an aspect hereof, R₄ can be a carboxylic acid moiety or derivative thereof, i.e., a carboxylic acid moiety or derivative which is bonded via its available oxygen atom to the C₄ atom of the tryptamine compound.

In some embodiments, in an aspect, the carboxylic acid moiety or derivative thereof can have the chemical formula (II):

-   -   wherein R_(4a) is an aryl group, a substituted aryl group, a         heteroaryl group, a substituted heteroaryl group, an alkyl         group, a substituted alkyl group, an amine group, or a         substituted amine group.

In some embodiments, the aryl group and substituted aryl group can be a phenyl group and a substituted phenyl group, respectively.

In some embodiments, the substituted aryl group can be a halo-substituted phenyl group.

In some embodiments, the alkyl group can be a C₁-C₁₀ alkyl group, in which optionally, at least one carbon atom in the alkyl chain is replaced with an oxygen (O) atom. For example, in a C₆ alkyl group two carbon atoms may be replaced with an O, or in a C₉ or C₈ alkyl chain three carbon atoms may be replaced with an O.

In some embodiments, the substituted alkyl group can be a C₁-C₁₀ alkyl group, wherein the optional substituents are at least one of halo, C₃-C₆ cycloalkyl, or amino (NH₂).

In some embodiments, the substituted alkyl group can be a C₁-C₁₀ alkyl group, wherein the optional substituent is a C₃-C₆ cycloalkane. The C₃-C₆ cycloalkane can be terminally attached to the C₁-C₁₀ alkyl group.

In some embodiments, the substituted alkyl group can be a C₁-C₁₀ alkyl group, wherein the optional substituent is cyclo-propane (C₃-cycloalkane). The cyclopropane can be terminally attached to the C₁-C₁₀ alkyl group.

In some embodiments, the substituted alkyl group can be a methyl group substituted by a cyclopropane group. In some embodiments, the substituted alkyl group can be a methyl group substituted by a cyclopropane group and an amino group.

In some embodiments, the aryl group can be a phenyl group in which two substituents on the phenyl group are joined together to form an additional 5-7-membered carbocyclic or heterocyclic ring.

In some embodiments, the 5-7-membered ring can be a methylene-dioxy ring, an ethylene-dioxy ring, or a dihydrofuryl ring.

In some embodiments, the substituted aryl group can be an optionally substituted phenyl group which is substituted with an acetamidyl group or an alkoxycarbonyl group, such as methoxycarbonyl (CH₃OC(═O)—), or a substituted carboxy group (—C(═O)O—R), including a carboxy group substituted with an indole group (R) or substituted indole group (R), wherein the substituted indole group can be substituted with a C₃-ethylamine or a C₃-substituted ethylamine, for example, a C₃-alkyl ethylamine, e.g., a C₃-methyl-substituted amine, a C₃-ethyl-substituted amine, or a C₃-propyl substituted amine.

In some embodiments, in an aspect, the substituted phenyl group can be an O-alkylated phenyl group.

In some embodiments, the substituted phenyl group can be an O-alkylated phenyl group, in which the phenyl group can be substituted with one or more O-alkyl groups.

In some embodiments, the O-alkyl group can be a methoxy group, an ethoxy group, a propoxy group, an iso-propoxy group, or a butoxy group (n-but, s-but or t-but).

In some embodiments, the O-alkyl group can be a methoxy group, for example, 1, 2, or 3 methoxy groups.

In some embodiments, the substituted phenyl group can be a halogenated phenyl group.

In some embodiments, the substituted phenyl group can be a per-halogenated phenyl group, such as a perfluorinated phenyl group.

In some embodiments, the substituted phenyl group can be a trifluoromethylated phenyl group (—CF₃), or a trifluromethoxy phenyl group (—OCF₃).

In some embodiments, the substituted aryl group can be a substituted phenyl group having one or more substituents which are independently selected from halo, alkoxy, alkyl, halo-substituted alkyl, or halo-substituted alkoxy. Thus, for example, the substituted phenyl group can be substituted with a trifluoromethyl group (—CF₃) and a methoxy group, or with a fluoro group and a methoxy group, or with a methyl group and a fluoro group, or with a trifluoromethyl group (—CF₃) and a trifluoromethoxy group (—OCF₃), and so forth.

In some embodiments, the phenyl group can be substituted with one or more of a trifluoromethoxy group (—OCF₃), a methoxy group or a halogen atom (fluoro, chloro, bromo, iodo).

In some embodiments, R_(4a) can be a substituted pyridine group.

In some embodiments, the substituted pyridine group can be an O-alkylated pyridine group, an O-arylated pyridine group or a halogenated pyridine group (chloro, fluoro, bromo, or iodo).

In some embodiments, the O-alkyl group can be a one or more methoxy groups, for example one or two groups.

In some embodiments, the substituted pyridine group can be an O-alkylated pyridine group, an O-arylated pyridine group, or a halogenated pyridine group.

In some embodiments, the O-alkylated pyridine group can be O-alkylated by one or more methoxy groups.

In some embodiments, the O-alkylated pyridine group can be O-alkylated by one or more methoxy groups and one or more halogen atoms (chloro, fluoro, bromo or iodo).

In some embodiments, the pyridine group can be substituted with a O-aryl group.

In some embodiments, the O-aryl group can be an O-phenyl group.

In some embodiments, the substituted aryl group can be a substituted phenyl group which is substituted by a carboxylate moiety.

In some embodiments, R_(4a) in formula (II) can be a substituted amine group wherein the substituent is —NH—CH₂R, where R is an organic radical. The organic radical can be any hydrocarbon radical, for example, an alkyl radical, or substituted alkyl radical, e.g., a C₁-C₆ alkyl radical, or a C₁-C₆ substituted alkyl radical, for example, a C₁-C₆ alkyl radical substituted with one or two amino groups or substituted amino groups, for example, R_(x)—NH—CH·—CH₂—CH₂—CH₂—NH—R_(y), wherein R_(x) and R_(y) can be independently selected from —(C═O)—NH₂ and —(C═O)(C(CHCH₃CH₃)NH)(C═O)(NH)CH₂CH₂CH₂CH₃ (wherein the organic radical is linked to be part of the amide substituent through the CH· carbon atom).

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(I):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(II):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(III):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(IV):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(V):

In some embodiments, in an aspect, in the compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(VI):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(VII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(VIII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(IX):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(X):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XI):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XIII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XIV):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XV):

In some embodiments, in an aspect, in the compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XVI):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XVII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XVIII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XIX):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XX):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXI):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXIII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXIV):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXV):

In some embodiments, in an aspect, in the compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXVI):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXVII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXVIII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXIX):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXX):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXXI):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXXII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXXIII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXXIV):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXXV):

In some embodiments, in an aspect, in the compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXXVI):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXXVII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXXVIII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XXXIX):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XL):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XLI):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XLII):

In an aspect, the present disclosure provides a compound having chemical formula (I) wherein R₄ is a carboxylic acid moiety or derivative thereof, the compound having the chemical formula C(XLIII):

Referring further to the compound having chemical formula (I), R_(3a) and R_(3b) can be independently a hydrogen atom or a (C₁-C₂₀)-alkyl group or an aryl group, for example a phenyl group. In another embodiment, R_(3a) and R_(3b) are independently a hydrogen atom or a (C₁-C₁₀)-alkyl group or an aryl group, for example a phenyl group. In another embodiment, R_(3a) and R_(3b) are independently a hydrogen atom or a (C₁-C₆)-alkyl group or an aryl group, for example a phenyl group. In another embodiment, R_(3a) and R_(3b) are independently a hydrogen atom, a methyl group, an ethyl group, or a propyl group, or an aryl group, for example a phenyl group. Thus, for example, R_(3a) and R_(3b) can each be a methyl group, ethyl group or propyl group, or one of R_(3a) and R_(3b) can be a methyl group, ethyl group or propyl group, and one of R_(3a) and R_(3b) can be a hydrogen atom, or one of R_(3a) and R_(3b) can be a phenyl group, and one of R_(3a) and R_(3b) can be a hydrogen atom.

-   -   Thus, to briefly recap, the present disclosure provides         C₄-carboxylic acid-substituted tryptamine derivatives. The         disclosure provides, in particular, a chemical compound having a         formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or derivative thereof,         and     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group. Example compounds, in         accordance with example embodiments, in his respect, include         each of compounds C(I), C(II), C(III), C(IV), C(V), C(VI),         C(VII), C(VIII), C(IX), C(X), C(XI), C(XII), C(XIII), C(XIV),         C(XV), C(XVI), C(XVII), C(XVIII), C(XIX), C(XX), C(XXI),         C(XXII), C(XXIII), C(XXIV), C(XXV), C(XXVI), C(XXVII),         C(XXVIII), C(XXIX), C(XXX), C(XXXI), C(XXXII), C(XXXIII),         C(XXXIV), C(XXXV), C(XXXVI), C(XXXVII), C(XXXVIII), C(XXXIX),         C(XL), C(XLI), C(XLII), and C(XLIII) set forth herein.

The C₄-carboxylic acid-substituted tryptamine derivatives of the present disclosure may be used to prepare a pharmaceutical or recreational drug formulation. Thus, in one embodiment, the present disclosure further provides in another aspect, pharmaceutical and recreational drug formulations comprising C₄-carboxylic acid-substituted tryptamine derivatives. Accordingly, in one aspect, the present disclosure provides in a further embodiment a pharmaceutical or recreational drug formulation comprising a chemical compound having a formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or derivative thereof,         and     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group.

The pharmaceutical or recreational drug formulations may be prepared as liquids, tablets, capsules, microcapsules, nanocapsules, trans-dermal patches, gels, foams, oils, aerosols, nanoparticulates, powders, creams, emulsions, micellar systems, films, sprays, ovules, infusions, teas, decoctions, suppositories, etc. and include a pharmaceutically acceptable salt or solvate of the C₄-substituted tryptamine derivative compound together with an excipient. The term “excipient” as used herein means any ingredient other than the chemical compound of the disclosure. In order to prepare a pharmaceutical drug formulation in accordance herewith, the C₄-carboxylic acid-substituted tryptamine derivative compounds are generally initially prepared and obtained in a substantially pure form, most preferably, at least in a 98%, 99% or 99.9% pure form, and thereafter formulated with a pharmaceutically acceptable excipient. As will readily be appreciated by those of skill in art, the selection of excipient may depend on factors such as the particular mode of administration, the effect of the excipient on solubility of the chemical compounds of the present disclosure and methods for their preparation will be readily apparent to those skilled in the art. Such compositions and methods for their preparation may be found, for example, in “Remington's Pharmaceutical Sciences”, 22^(nd) Edition (Pharmaceutical Press and Philadelphia College of Pharmacy at the University of the Sciences, 2012).

The dose when using the compounds of the present disclosure can vary within wide limits, and as is customary and is known to those of skill in the art, the dose can be tailored to the individual conditions in each individual case. The dose depends, for example, on the nature and severity of the illness to be treated, on the condition of the patient, on the compound employed or on whether an acute or chronic disease state is treated, or prophylaxis is conducted, on the mode of delivery of the compound, or on whether further active compounds are administered in addition to the compounds of the present disclosure. Representative doses of the present invention include, but are not limited to, about 0.001 mg to about 5000 mg, about 0.001 mg to about 2500 mg, about 0.001 mg to about 1000 mg, about 0.001 mg to about 500 mg, about 0.001 mg to about 250 mg, about 0.001 mg to about 100 mg, about 0.001 mg to about 50 mg, and about 0.001 mg to about 25 mg. Representative doses of the present disclosure include, but are not limited to, about 0.0001 to about 1,000 mg, about 10 to about 160 mg, about 10 mg, about 20 mg, about 40 mg, about 80 mg or about 160 mg. Multiple doses may be administered during the day, especially when relatively large amounts are deemed to be needed, for example 2, 3 or 4, doses. Depending on the subject and as deemed appropriate from the patient's physician or care giver it may be necessary to deviate upward or downward from the doses described herein.

The pharmaceutical and drug formulations comprising the C₄-carboxylic acid-substituted tryptamine derivative compounds of the present disclosure may be administered orally. Oral administration may involve swallowing, so that the compound enters the gastrointestinal tract, or buccal or sublingual administration may be employed by which the compound enters the blood stream directly from the mouth. Formulations suitable for oral administration include both solid and liquid formulations.

Solid formulations include tablets, capsules (containing particulates, liquids, microcapsules, or powders), lozenges (including liquid-filled lozenges), chews, multi- and nano-particulates, gels, solid solutions, liposomal preparations, microencapsulated preparations, creams, films, ovules, suppositories, and sprays.

Liquid formulations include suspensions, solutions, syrups, and elixirs. Such formulations may be employed as fillers in soft or hard capsules and typically comprise a carrier, for example, water, ethanol, polyethylene glycol, propylene glycol, methylcellulose, or a suitable oil, and one or more emulsifying agents and/or suspending agents. Liquid formulations may also be prepared by the reconstitution of a solid, for example, from a sachet.

Binders are generally used to impart cohesive qualities to a tablet formulation. Suitable binders include microcrystalline cellulose, gelatin, sugars, polyethylene glycol, natural and synthetic gums, polyvinylpyrrolidone, pregelatinized starch, hydroxypropyl cellulose and hydroxypropyl methylcellulose.

Tablets may also contain diluents, such as lactose (monohydrate, spray-dried monohydrate, anhydrous and the like), mannitol, xylitol, dextrose, sucrose, sorbitol, microcrystalline cellulose, starch, and dibasic calcium phosphate dihydrate.

Tablets may also optionally comprise surface active agents, such as sodium lauryl sulfate and polysorbate 80. When present, surface active agents may comprise from 0.2% (w/w) to 5% (w/w) of the tablet.

Tablets may further contain lubricants such as magnesium stearate, calcium stearate, zinc stearate, sodium stearyl fumarate, and mixtures of magnesium stearate with sodium lauryl sulphate. Lubricants generally comprise from 0.25% (w/w) to 10% (w/w), from 0.5% (w/w) to 3% (w/w) of the tablet.

In addition to the C₄-carboxylic acid-substituted tryptamine derivative compounds, tablets may contain a disintegrant. Examples of disintegrants include sodium starch glycolate, sodium carboxymethyl cellulose, calcium carboxymethyl cellulose, croscarmellose sodium, crospovidone, polyvinylpyrrolidone, methyl cellulose, microcrystalline cellulose, lower alkyl-substituted hydroxypropyl cellulose, starch, pregelatinized starch and sodium alginate. Generally, the disintegrant will comprise from 1% (w/w) to 25% (w/w) or from 5% (w/w) to 20% (w/w) of the dosage form.

Other possible auxiliary ingredients include anti-oxidants, colourants, flavouring agents, preservatives, and taste-masking agents.

For tablet dosage forms, depending on the desired effective amount of the chemical compound, the chemical compound of the present disclosure may make up from 1% (w/w) to 80% (w/w) of the dosage form, more typically from 5% (w/w) to 60% (w/w) of the dosage form.

Example tablets contain up to about 80% (w/w) of the chemical compound, from about 10% (w/w) to about 90% (w/w) binder, from about 0% (w/w) to about 85% (w/w) diluent, from about 2% (w/w) to about 10% (w/w) disintegrant, and from about 0.25% (w/w) to about 10% (w/w) lubricant.

The formulation of tablets is discussed in “Pharmaceutical Dosage Forms: Tablets”, Vol. 1-Vol. 3, by CRC Press (2008).

The pharmaceutical and recreational drug formulations comprising the C₄-carboxylic acid-substituted tryptamine derivative compound of the present disclosure may also be administered directly into the blood stream, into muscle, or into an internal organ. Thus, the pharmaceutical and recreational drug formulations can be administered parenterally (for example, by subcutaneous, intravenous, intraarterial, intrathecal, intraventricular, intracranial, intramuscular, or intraperitoneal injection). Parenteral formulations are typically aqueous solutions which may contain excipients such as salts, carbohydrates, and buffering agents (in one embodiment, to a pH of from 3 to 9), but, for some applications, they may be more suitably formulated as a sterile non-aqueous solution or as a dried form to be used in conjunction with a suitable vehicle such as sterile water.

Formulations comprising the C₄-carboxylic acid-substituted tryptamine derivative compound of the present disclosure for parenteral administration may be formulated to be immediate and/or modified release. Modified release formulations include delayed-, sustained-, pulsed-, controlled-, targeted and programmed release. Thus, the chemical compounds of the disclosure may be formulated as a solid, semi-solid, or thixotropic liquid for administration as an implanted depot providing modified release of the active compound. Examples of such formulations include drug-coated stents and poly(dl-lactic-coglycolic)acid (PGLA) microspheres.

The pharmaceutical or recreational drug formulations of the present disclosure also may be administered topically to the skin or mucosa, i.e., dermally or transdermally. Example pharmaceutical and recreational drug formulations for this purpose include gels, hydrogels, lotions, solutions, creams, ointments, dusting powders, cosmetics, oils, eye drops, dressings, foams, films, skin patches, wafers, implants, sponges, fibres, bandages and microemulsions. Liposomes may also be used. Example carriers include alcohol, water, mineral oil, liquid petrolatum, white petrolatum, glycerin, polyethylene glycol and propylene glycol. Penetration enhancers may be incorporate (see: for example, Finnin, B. and Morgan, T. M., 1999 J. Pharm. Sci, 88 (10), 955-958).

Other means of topical administration include delivery by electroporation, iontophoresis, phonophoresis, sonophoresis and microneedle or needle-free (e.g., Powderject™, Bioject™, etc.) injection.

Pharmaceutical and recreational drug formulations for inhalation or insufflation include solutions and suspensions in pharmaceutically acceptable, aqueous, or organic solvents, or mixtures thereof, and powders. The liquid or solid pharmaceutical compositions can contain suitable pharmaceutically acceptable excipients. In some embodiments, the pharmaceutical compositions are administered by the oral or nasal respiratory route for local or systemic effect. Pharmaceutical compositions in pharmaceutically acceptable solvents can be nebulized by use of inert gases. Nebulized solutions can be inhaled directly from the nebulizing device, or the nebulizing device can be attached to a face mask tent, or intermittent positive pressure breathing machine. Solution, suspension, or powder pharmaceutical compositions can be administered, e.g., orally, or nasally, from devices that deliver the formulation in an appropriate manner.

It is noted that in some embodiments, the chemical compounds in the pharmaceutical formulation may act as pro-drugs. Pro-drugs represent a modality to control drug bioavailability, control timing of drug release, and/or reduce negative side-effects. Similarly, formulation and delivery considerations can achieve these outcomes. Thus, adjustment and optimization of all three variables together (prodrug moiety, formulation, delivery system) can be an effective strategy in drug development. Examples of ‘targeting systems’ designed to specifically reach cells within the brain, obtained by simultaneously leveraging pro-drug, nanoparticle. And nasal administration strategies are described, for example by Botti et al., 2021 Pharmaceutics 13:1114).

In further embodiments, in which the C₄-carboxylic acid-substituted tryptamine derivative compounds of present disclosure are used as a recreational drug, the compounds may be included in compositions such as a food or food product, a beverage, a food seasoning, a personal care product, such as a cosmetic, perfume or bath oil, or oils (both for topical administration as massage oil, or to be burned or aerosolized). The chemical compounds of the present disclosure may also be included in a “vape” product, which may also include other drugs, such as nicotine, and flavorings.

Thus, it will be clear that the C₄-carboxylic acid-substituted tryptamine derivative compounds may be used as a pharmaceutical or recreational drug. Accordingly, in another aspect the present disclosure provides, in at least one embodiment, a use of a chemical compound having a formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or derivative thereof,         and     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group, as a pharmaceutical or         recreational drug

The pharmaceutical formulations comprising the chemical compounds of the present disclosure may be used to treat a subject, and to treat a brain neurological disorder in a subject. Accordingly, the present disclosure includes in a further embodiment, a method for treating a brain neurological disorder, the method comprising administering to a subject in need thereof a pharmaceutical formulation comprising a chemical compound having a formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or derivative thereof;         and     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group, wherein the         pharmaceutical formulation is administered in an effective         amount to treat the brain neurological disorder.

Brain neurological disorders include psychiatric disorders that may be treated include, for example, neurodevelopmental disorders such as intellectual disability, global development delay, communication disorders, autism spectrum disorder, and attention-deficit hyperactivity disorder (ADHD); bipolar and related disorders, such as mania, and depressive episodes; anxiety disorder, such as generalized anxiety disorder (GAD), agoraphobia, social anxiety disorder, specific phobias (natural events, medical, animal, situational, for example), panic disorder, and separation anxiety disorder; stress disorders, such as acute stress disorder, adjustment disorders, post-traumatic stress disorder (PTSD), and reactive attachment disorder; dissociative disorders, such as dissociative amnesia, dissociative identity disorder, and depersonalization/derealization disorder; somatoform disorders, such as somatic symptom disorders, illness anxiety disorder, conversion disorder, and factitious disorder; eating disorders, such as anorexia nervosa, bulimia nervosa, rumination disorder, pica, and binge-eating disorder; sleep disorders, such as narcolepsy, insomnia disorder, hypersomnolence, breathing-related sleep disorders, parasomnias, and restless legs syndrome; disruptive disorders, such as kleptomania, pyromania, intermittent explosive disorder, conduct disorder, and oppositional defiant disorder; depressive disorders, such as disruptive mood dysregulation disorder, major depressive disorder (MDD), persistent depressive disorder (dysthymia), premenstrual dysphoric disorder, substance/medication-induced depressive disorder, postpartum depression, and depressive disorder caused by another medical condition, for example, psychiatric and existential distress within life-threatening cancer situations (ACS Pharmacol. Transl. Sci. 4: 553-562; J. Psychiatr. Res. 137: 273-282); substance-related disorders, such as alcohol-related disorders, cannabis related disorders, inhalant-use related disorders, stimulant use disorders, and tobacco use disorders; neurocognitive disorders, such as delirium; schizophrenia; compulsive disorders, such as obsessive compulsive disorders (OCD), body dysmorphic disorder, hoarding disorder, trichotillomania disorder, excoriation disorder, substance/medication induced obsessive-compulsive disorder, and obsessive-compulsive disorder related to another medical condition; and personality disorders, such as antisocial personality disorder, avoidant personality disorder, borderline personality disorder, dependent personality disorder, histrionic personality disorder, narcissistic personality disorder, obsessive-compulsive personality disorder, paranoid personality disorder, schizoid personality disorder, and schizotypal personality disorder. Brain neurological disorders further include headache disorders, including migraines, including, for example, aural migraine, non-aural migraine, menstrual migraine, chronic migraine, vestibular migraine, abdominal migraine, hemiplegic migraine, and other headache disorders.

In an aspect, the compounds of the present disclosure may be used to be contacted with a receptor to thereby modulate the receptor. Such contacting includes bringing a compound of the present disclosure and receptor together under in vitro conditions, for example, by introducing the compounds in a sample containing a receptor, for example, a sample containing purified receptors, or a sample containing cells comprising receptors. In vitro conditions further include the conditions described in Example 1 hereof. Contacting further includes bringing a compound of the present disclosure and receptor together under in vivo conditions. Such in vivo conditions include the administration to an animal or human subject, for example, of a pharmaceutically effective amount of the compound of the present disclosure, when the compound is formulated together with a pharmaceutically active carrier, diluent, or excipient, as hereinbefore described, to thereby treat the subject. Upon having contacted the receptor, the compound may activate the receptor or inhibit the receptor.

In an aspect receptors with which the compounds of the present disclosure may be contacted include, for example, the 5-HT_(1A) receptor, the 5-HT_(2A) receptor, the 5-HT_(1B) receptor, the 5-HT_(2B) receptor, the 5-HT_(3A) receptor, the ADRA1A receptor, the ADRA2A receptor, the CHRM1 receptor, the CHRM2 receptor, the CNR1 receptor, the DRD1 receptor, the DRD2S receptor, or the OPRD1 receptor.

Thus, in a further aspect, the condition that may be treated in accordance herewith can be any receptor mediated disorder, including, for example, a 5-HT_(1A) receptor-mediated disorder, a 5-HT_(2A) receptor-mediated disorder, a 5-HT_(1B) receptor-mediated disorder, a 5-HT_(2B) receptor-mediated disorder, a 5-HT_(3A) receptor-mediated disorder, a ADRA1A receptor-mediated disorder, a ADRA2A receptor-mediated disorder, a CHRM1 receptor-mediated disorder, a CHRM2 receptor-mediated disorder, a CNR1 receptor-mediated disorder, a DRD1 receptor-mediated disorder, a DRD2S receptor-mediated disorder, or a OPRD1 receptor-mediated disorder. Such disorders include, but are not limited to schizophrenia, psychotic disorder, attention deficit hyperactivity disorder, autism, and bipolar disorder.

In some embodiments, upon having contacted a receptor and a receptor, the compound may modulate the receptor. However at the same time other receptors may not be modulated. E.g., a compound may activate or inhibit a first receptor, e.g., a 5-HT_(1A) receptor, however the compound may at the same time not modulate a second receptor, e.g., a 5-HT_(2A) receptor, or upon having contacted a first 5-HT_(2A) receptor and a second 5-HT_(1A) receptor, the compound may modulate the first 5-HT_(2A) receptor, e.g., activate or inhibit the 5-HT_(2A) receptor, however the compound may at the same time not modulate the second 5-HT_(1A) receptor.

In one embodiment, in an aspect, upon administration the compounds of the present disclosure can interact with an enzyme or transmembrane transport protein in the subject to thereby modulate the enzyme or transmembrane transport protein and exert a pharmacological effect. Such contacting includes bringing a compound of the present disclosure and enzyme or transmembrane transport protein together under in vitro conditions, for example, by introducing the compounds in a sample containing an enzyme or transmembrane transport protein, for example, a sample containing a purified enzyme or transmembrane transport protein, or a sample containing cells comprising an enzyme or transmembrane transport protein. Contacting further includes bringing a compound of the present disclosure and an enzyme or transmembrane transport protein together under in vivo conditions. Such in vivo conditions include the administration to an animal or human subject, for example, of a pharmaceutically effective amount of the compound of the present disclosure, when the compound is formulated together with a pharmaceutically active carrier, diluent, or excipient, as hereinbefore described, to thereby treat the subject.

In one embodiment, in an aspect, the enzyme can be monoamine oxidase A (MOA-A),

In one embodiment, in an aspect, the transmembrane transport protein can be a dopamine active transporter (DAT), a norephedrine transporter (NET), or a serotonin transporter (SERT) transmembrane transport protein.

It is noted that in one embodiment, in an aspect, upon administration the compound having formula (I) may be in vivo hydrolyzed to form a compound having chemical formula (VI):

-   -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group,     -   and wherein the compound having chemical formula (VI) interacts         with a receptor to thereby modulate the receptor in the subject         and exert a pharmacological effect. In this respect, the         compounds of the present disclosure may be formulated as a         pro-drug pharmaceutical formulation, i.e., a formulation wherein         it is not the formulated compound itself that mediates a         pharmacological effect, but rather a compound that is obtained         following in vivo hydrolyzation of the formulated compound by         the subject. Hydrolyzation may occur, for example, in the         gastro-intestinal tract of a person upon oral delivery of a         pro-drug pharmaceutical formulation.

Turning now to methods of making the C₄-carboxylic acid-substituted tryptamine derivative compounds of the present disclosure, it is initially noted, by way of general comment that the C₄-carboxylic acid-substituted tryptamine derivative compounds of the present disclosure may be prepared in any suitable manner, including by any organic chemical synthesis methods, biosynthetic methods, or a combination thereof.

Examples of suitable chemical reactions that may be performed in accordance herewith are depicted in FIGS. 3A (i), 3A (ii), 4A, 5A, 6A, 7A, 8A, 9A and 10A, and are further additionally detailed hereinafter in the Example section.

In general, as is known to those of skill in the art, in order to perform chemical synthetic reactions selected reactants are reacted under reaction conditions which permit the reactants to chemically react with each other and form a product, i.e., the C₄-carboxylic acid-substituted tryptamine derivative compounds of the present disclosure. Such reactions conditions may be selected, adjusted, and optimized as known by those of skill in the art. The reactions may be conducted in any suitable reaction vessel (e.g., a tube, bottle). Suitable solvents that may be used are polar solvents such as, for example, dichloromethane, dichloroethane, toluene, and so called participating solvents such as acetonitrile and diethyl ether. Suitable temperatures may range from, for example, e.g., from about −78° C. to about 60° C. Furthermore, catalysts, also known as promoters, may be included in the reaction such as iodonium dicollidine perchlorate (IDCP), any silver or mercury salts, trimethylsilyl trifluoromethanesulfonate (TMS-triflate, TMSOTf), or trifluoronmethanesulfonic acid (triflic acid, TfOH), N-iodosuccinimide, methyl triflate. Furthermore, reaction times may be varied. As will readily be appreciated by those of skill in the art, the reaction conditions may be optimized, for example, by preparing several reactant preparations and reacting these in separate reaction vessels under different reaction conditions, for example, different temperatures, using different solvents etc., evaluating the obtained C₄-carboxylic acid-substituted tryptamine derivative compounds product, adjusting reaction conditions, and selecting a desired reaction condition.

In accordance with the foregoing, in aspect, disclosed herein are methods of making a chemical compound having chemical formula (I):

-   -   wherein R₄ is a carboxylic acid moiety or a derivative thereof,         and     -   wherein R_(3a) and R_(3b) are each independently a hydrogen         atom, an alkyl group, or an aryl group, wherein the method         involves the performance of at least one chemical synthesis         reaction selected from the reactions depicted in FIGS. 3A (i),         3A (ii), 4A, 5A, 6A, 7A, 8A, 9A, or 10A.

Referring to FIGS. 3A (i) and 3A (ii), in one embodiment, the compound having chemical formula (I) can be a compound having formula C(V):

and the at least one chemical synthesis reaction is the chemical synthesis reaction depicted in FIG. 3A (i) or FIG. 3A (ii).

Referring next to FIG. 4A, in one embodiment, the compound having chemical formula (I) can be a compound having formula C(VI):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 4A.

Referring next to FIG. 5A, in one embodiment, the compound having chemical formula (I) can be a compound having formula C(VII):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 5A.

Referring next to FIG. 6A, one embodiment, the compound having chemical formula (I) can be a compound having formula C(III):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 6A.

Referring next to FIG. 7A, in one embodiment, the compound having chemical formula (I) can be a compound having formula C(XLIII):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 7A.

Referring next to FIG. 8A, in one embodiment, the compound having chemical formula (I) can be a compound having formula C(I):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 8A.

Referring next to FIG. 9A, one embodiment, the compound having chemical formula (I) can be a compound having formula C(XX):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 9A.

Referring next to FIG. 10A, in one embodiment, the compound having chemical formula (I) can be a compound having formula C(IV):

-   -   and the at least one chemical synthesis reaction is the chemical         synthesis reaction depicted in FIG. 10A.

In some embodiments, the chemical compounds may be isolate in pure or substantially pure form. Thus the compounds may be, for example, at least 90%, 95%, 96%, 97%, or 98%, or at least 99% pure.

It will now be clear from the foregoing that novel C₄-carboxylic acid-substituted tryptamine derivatives are disclosed herein. The C₄-carboxylic acid-substituted tryptamine derivatives may be formulated for use as a pharmaceutical drug or recreational drug. Example embodiments and implementations of the present disclosure are further illustrated by the following examples.

EXAMPLES Example 1—Synthesis and Analysis of a First C₄-Carboxylic Acid-Substituted Tryptamine Derivative

Two example syntheses methods for a first C₄-carboxylic acid-substituted tryptamine derivative are described in this Example 1. A first method afforded a final product at 9% yield, and was performed at a small scale (18 mg product) as follows. Referring to FIG. 3A (i), to a suspension of compound (1) (16 mg) in dry dichloromethane (DCM) (10 ml) was added 22 μl of triethylamine dropwise and 4-methoxylbenzoyl chloride (27 mg). Notably, the synthesis of psilocin (1) has been described previously (Shirota et al., J. Nat. Prod. 2003, 66:885-887; Kargbo et al., ACS Omega 2020, 5:16959-16966). After stirring for 5 minutes at room temperature, the mixture turned to clear solution. The mixture was stirred at room temperature for 1-2 hours and the reaction was monitored by thin layer chromatography (TLC). The reaction was then quenched by diluted aqueous HCl (0.5N) and extracted with DCM three times. The combined organic extracts were washed with water, brine. Then dried over anhydrous MgSO₄. After concentration using a rotary evaporator, the mixture residue was applied to a silica column for chromatographic purification, eluting with 5% methanol in DCM to afford compound (2) as an off-white solid (18.1 mg, 9% yield). ¹H NMR (CDCl₃): δ 9.43 (1H, s, NH), 8.22 (2H, m, ArH), 7.35 (1H, dd, ArH), 7.15 (1H, t, ArH), 7.04 (2H, d, ArH), 6.91 (1H, m, ArH), 6.83 (1H, m, ArH), 3.92 (3, s, OCH3), 3.11 (2H, m, CH₂), 2.97 (2H, m, CH₂), 2.37 (6H, d, NCH3). LCMS results: cal mass for C₂₀H₂₃N₂O₃ [M+H]: 339.1703, found: 339.1700. Purity was determined to be 95%. It is noted that compound (2) corresponds with the chemical compound having chemical formula: C(V):

A second method to synthesize a compound having chemical formula C(V) improved upon the first method, as the latter afforded 74% yield and was performed on a comparatively larger scale (250 mg product) as follows. Referring to FIG. 3A (ii), a solution of psilocin 1 (200 mg, 979 μmol) and triethylamine (274 μL, 1.96 mmol) in DCM (8.0 mL) was cooled down to 0° C. To it was added 4-methoxybenzoyl chloride (192 mg, 1.12 mmol) in DCM (0.5 mL). The resulting mixture was warmed up to RT and stirred for 2 hours. At this time, another portion of 4-methoxybenzoyl chloride (192 mg, 1.12 mmol) in DCM (0.5 mL) was added, and the reaction was stirred at RT for another hour. Methanol (2 mL) was added to the reaction, and the volatiles were removed in vacuo. The crude residue was directly purified by flash chromatography (FC) on silica gel (12 g, MeOH/DCM 0:100 to 20:80, 10 CV, product eluting at 11% methanol) to afford the product as a brown oil. TLC showed co-elution of p-methoxybenzoic acid with the product. This isolated material was re-dissolved in DCM (50 mL), and extracted with saturated aqueous NaHCO₃ (2×30 mL). The aqueous layer was back-extracted with DCM (xl), washed with brine, dried over anhydrous Na₂SO₄, filtered and concentrated to afford the pure product 2 as an off-white foamy solid (245 mg, 74%). MS-ESI: calculated m/z for C₂₀H₂₃N₂O₃ [M+H]⁺: 339.1703, found: 339.1700. ¹H NMR (400 MHz, CDCl₃) δ 8.27-8.21 (m, 3H), 7.23 (dd, J=8.2, 1.0 Hz, 1H), 7.17 (t, J=7.8 Hz, 1H), 7.03-6.98 (m, 2H), 6.95 (dd, J=2.3, 1.1 Hz, 1H), 6.88 (dd, J=7.6, 1.0 Hz, 1H), 3.90 (s, 3H), 2.92-2.84 (m, 2H), 2.60-2.52 (m, 2H), 2.09 (s, 6H). Purity was determined to be 95%. It is noted that compound (2) corresponds with the chemical compound having chemical formula C(V).

Assessment of Cell Viability Upon Treatment of a Psilocin Derivative.

To establish suitable ligand concentrations for competitive binding assays, PrestoBlue assays were first performed. The PrestoBlue assay measures cell viable activity based on the metabolic reduction of the redox indicator resazurin, and is a preferred method for routine cell viability assays (Terrasso et al., 2017, J. Pharmacol. Toxicol. Methods 83: 72). Results of these assays were conducted using both control ligands (e.g., psilocybin, psilocin, DMT, tryptophan) and novel derivatives, in part as a pre-screen for any remarkable toxic effects on cell cultures up to concentrations of 1 mM. A known cellular toxin (Triton X-100, Pyrgiotakis G. et al., 2009, Ann. Biomed. Eng. 37: 1464-1473) was included as a general marker of toxicity. Drug-induced changes in cell health within simple in vitro systems such as the HepG2 cell line are commonly adopted as first-line screening approaches in the pharmaceutical industry (Weaver et al., 2017, Expert Opin. Drug Metab. Toxicol. 13: 767). HepG2 is a human hepatoma that is most commonly used in drug metabolism and hepatotoxicity studies (Donato et al., 2015, Methods Mol Biol 1250: 77). Herein, HepG2 cells were cultured using standard procedures using the manufacture's protocols (ATCC, HB-8065). Briefly, cells were cultured in Eagle's minimum essential medium supplemented with 10% fetal bovine serum and grown at 37° C. in the presence of 5% CO₂. To test the various compounds with the cell line, cells were seeded in a clear 96-well culture plate at 20,000 cells per well. After allowing cells to attach and grow for 24 hours, compounds were added at 1 mM, 10 mM, 100 mM, and 1 mM. Methanol or DMSO were used as vehicles, at concentrations 0, 0.001, 0.01, 0.1, and 1% (methanol) or 0, 0.001, 0.01, 0.1, and 1% (DMSO), respectively. As a positive control for toxicity, TritonX concentrations used were 0.0001, 0.001, 0.01 and 0.1%. Cells were incubated with compounds for 48 hours before assessing cell viability with the PrestoBlue assay following the manufacture's protocol (ThermoFisher Scientific, P50200). PrestoBlue reagent was added to cells and allowed to incubate for 1 hour before reading. Absorbance readings were performed at 570 nm with the reference at 600 nm on a SpectraMax iD3 plate reader. Non-treated cells were assigned 100% viability. Bar graphs show the mean+/−SD, n=3. Significance was determined by 2-way ANOVA followed by Dunnett's multiple comparison test and is indicated by *** (P<0.0001), **(P<0.001), *(P<0.005). Data acquired for the derivative having chemical formula (C-V) is displayed as “C-V” on the x-axes in FIG. 3B and FIG. 3C.

Radioligand Receptor Binding Assays.

Evaluation of drug binding is an essential step to characterization of all drug-target interactions (Fang 2012, Exp. Opin. Drug Discov. 7:969). The binding affinity of a drug to a target is traditionally viewed as an acceptable surrogate of its in vivo efficacy (Nüñez et al., 2012, Drug Disc Today 17: 10). Competition assays, also called displacement or modulation binding assays, are a common approach to measure activity of a ligand at a target receptor (Flanagan 2016, Methods Cell Biol 132: 191). In these assays, standard radioligands acting either as agonists or antagonists are ascribed to specific receptors. In the case of G protein-coupled receptor 5-HT_(2A), [³H]ketanserin is a well-established antagonist used routinely in competition assays to evaluate competitive activity of novel drug candidates at the 5-HT_(2A) receptor (Maguire et al., 2012, Methods Mol Biol 897: 31). Thus, to evaluate activity of novel C₄-substituted tryptamine derivatives at the 5-HT_(2A) receptor, competition assays using [³H]ketanserin were employed as follows. SPA beads (RPNQ0010), [³H] ketanserin (NET1233025UC), membranes containing 5-HT_(2A) (ES-313-M400UA), and isoplate-96 microplate (6005040) were all purchased from PerkinElmer. Radioactive binding assays were carried out using Scintillation Proximity Assay (SPA). For saturation binding assays, mixtures of 10 ug of membrane containing 5-HT_(2A) receptor was pre-coupled to 1 mg of SPA beads at room temperature in a tube rotator for 1 hour in binding buffer (50 mM Tris-HCl pH7.4, 4 mM CaCl₂, 1 mM ascorbic acid, 10 mM pargyline HCl). After pre-coupling, the beads and membrane were aliquoted in an isoplate-96 microplate with increasing amounts of [³H]ketanserin (0.1525 nM to 5 nM) and incubated for two hours at room temperature in the dark with shaking. After incubation, the samples were read on a MicroBeta 2 Microplate Counter (Perkin Elmer). Determination of non-specific binding was carried out in the presence of 20 mM of spiperone (S7395-250MG, Sigma). Equilibrium binding constants for ketanserin (K_(d)) were determined from saturation binding curves using the ‘one-site saturation binding analysis’ method of GraphPad PRISM software (Version 9.2.0). Competition binding assays were performed using fixed (1 nM) [³H]ketanserin and different concentrations of tryptophan (3 nM to 1 mM), psilocin (30 pM to 10 mM) or unlabeled test compound (3 nM to 1 mM) similar to the saturation binding assay. K_(i) values were calculated from the competition displacement data using the competitive binding analysis from GraphPad PRISM software. Tryptophan was included as a negative control as it has no activity at the 5-HT_(2A) receptor. In contrast, psilocin was used as a positive control since it has established binding activity at the 5-HT_(2A) receptor (Kim et al., 2020, Cell 182: 1574). FIG. 3D depicts the saturation binding curves for [³H]ketanserin at the 5-HT_(2A) receptor. Panel A shows the specific saturation ligand binding of [³H]ketanserin (from 0.1525 nM to 5 nM) to membranes containing 5-HT_(2A) receptor, which was obtained after subtracting non-specific binding values (shown in Panel B). Specific binding in counts per minute (cpm) was calculated by subtracting non-specific binding from total binding. Specific binding (pmol/mg) was calculated from pmol of [³H]ketanserin bound per mg of protein in the assay. The K_(d) was calculated by fitting the data with the one-site binding model of PRISM software (version 9.2.0). FIG. 3E shows the competition binding curves for psilocin as a positive control (binding). This assay was conducted twice, yielding data shown in Panels A and B, respectively. FIG. 3F shows the competition binding curves for psilocybin (Panel A) and tryptophan (Panel B). Psilocybin is known to release the 5-HT_(2A)-binding metabolite psilocin in vivo; however, the intact psilocybin molecule itself displays very weak (McKenna and Peroutka 1989, J Neurosci 9: 3482) or arguably negligible (PDSP Certified Data; https://pdsp.unc.edu/databases/pdsp.php) binding at 5-HT_(2A). Tryptophan is included as a negative control (no binding). The competition binding curve for compound with formula C(V), designated “C-V” in FIG. 3G.

Cell Lines and Control Ligands Used to Assess Activity at 5-HT_(IA).

CHO-K1/Ga₁₅ (GenScript, M00257) (−5-HT_(1A)) and CHO-K1/5-HT_(1A)/Ga₁₅ (GenScript, M00330) (+5-HT_(1A)) cells lines were used. Briefly, CHO-K1/Ga₁₅ is a control cell line that constitutively expresses Ga₁₅ which is a promiscuous G_(q) protein. This control cell line lacks any transgene encoding 5-HT_(1A) receptors, but still responds to forskolin; thus, cAMP response to forskolin should be the same regardless of whether or not 5-HT_(1A) agonists are present. Conversely, CHO-K1/5-HT_(1A)/Ga₁₅ cells stably express 5-HT_(1A) receptor in the CHO-K1 host background. Notably, Ga₁₅ is a promiscuous G protein known to induce calcium flux response, present in both control and 5-HT_(1A) cell lines. In +5-HT_(1A) cells, Ga₁₅ may be recruited in place of G_(ai/o), which could theoretically dampen cAMP response (Rojas and Fiedler 2016, Front Cell Neurosci 10: 272). Thus, we included two known 5-HT_(1A) agonists, DMT (Cameron and Olson 2018, ACS Chem Neurosci 9: 2344) and serotonin (Rojas and Fiedler 2016, Front Cell Neurosci 10: 272) as positive controls to ensure sufficient cAMP response was observed, thereby indicating measurable recruitment of G_(ai/o) protein to activated 5-HT_(1A) receptors. In contrast, tryptophan is not known to activate 5-HT_(1A) receptors, and was thus used as a negative control. Cells were maintained in complete growth media as recommended by supplier (GenScript) which is constituted as follows: Ham's F12 Nutrient mix (HAM's F12, GIBCO #11765-047) with 10% fetal bovine serum (FBS) (Thermo Scientific #12483020), 200 mg/ml zeocin (Thermo Scientific #R25005) and/or 100 mg/ml hygromycin (Thermo Scientific #10687010). The cells were cultured in a humidified incubator with 37° C. and 5% CO₂. Cells maintenance was carried out as recommended by the cell supplier. Briefly, vials with cells were removed from the liquid nitrogen and thawed quickly in 37° C. water bath. Just before the cells were completely thawed the vial's outside was decontaminated by 70% ethanol spray. The cell suspension was then retrieved from the vial and added to warm (37° C.) complete growth media, and centrifuged at 1,000 rpm for 5 minutes. The supernatant was discarded, and the cell pellet was then resuspended in another 10 ml of complete growth media, and added to the 10 cm cell culture dish (Greiner Bio-One #664160). The media was changed every third day until the cells were about 90% confluent. The ˜90% confluent cells were then split 10:1 for maintenance or used for experiment.

Evaluation of 5-HT₁A Receptor Modulation.

As 5-HT_(1A) activation inhibits cAMP formation, the agonist activity of test molecules on 5-HT_(1A) was measured via the reduction in the levels of cAMP produced due to application of 4 mM forskolin. The change in intracellular cAMP levels due to the treatment of novel molecules was measured using cAMP-Glo Assay kit (Promega #V1501). Briefly, +5-HT_(1A) cells were seeded on 1-6 columns and base −5-HT_(1A) cells were seeded on columns 7-12 of the white walled clear bottom 96-well plate (Corning, #3903). Both cells were seeded at the density of 30,000 cells/well in 100 ml complete growth media and cultured 24 hrs in humidified incubator at 37° C. and 5% CO₂. On the experiment day, the media of cells was replaced with serum/antibiotic free culture media. Then the cells were treated for 20 minutes with test molecules dissolved in induction medium (serum/antibiotic free culture media containing 4 mM forskolin, 500 mM IBMX (isobutyl-1-methylxanthine, Sigma-Aldrich, Cat. #17018) and 100 mM (RO 20-1724, Sigma-Aldrich, Cat. #B8279)). Forskolin induced cAMP formation whereas IBMX and RO 20-1724 inhibited the degradation of cAMP. The level of luminescence in cells incubated with induction medium (containing 4 mM forskolin) without test molecules was normalized to represent 100% cAMP in this assay. PKA was added to the lysate, mixed, and subsequently the substrate of the PKA was added. PKA was activated by cAMP, and the amount of ATP consumed due to PKA phosphorylation directly corresponded to cAMP levels in the lysate. Reduced ATP caused reduced conversion of luciferin to oxyluciferin, conferring diminished luminescence as the result of 5-HT_(1A) activation. FIG. 3H shows increasing levels of cAMP in cultured cells incubated with increasing concentrations of forskolin independent of 5-HT_(1A) expression. FIG. 3I illustrates no reduction in cellular cAMP levels in either cell culture (+5-HT_(1A) and −5-HT_(1A)) stimulated with induction medium and treated with increasing doses of tryptophan, indicating a lack of 5-HT_(1A) activity by this molecule in +5-HT_(1A) cells. FIG. 3J illustrates reduction in cAMP levels in 5-HT_(1A) receptor expressing cells (+5-HT_(1A)) stimulated with 4 mM forskolin as levels of psilocin increase, indicating 5-HT_(1A) receptor binding by psilocin in these cells. Conversely, this trend of decreasing % cAMP levels with increasing psilocin is not observed in cells lacking expression of 5-HT_(1A) receptor. FIG. 3K illustrates reduction in cAMP levels in 5-HT_(1A) receptor expressing cells stimulated with 4 mM forskolin as levels of serotonin (5-HT) increase, indicating 5-HT_(1A) receptor binding by serotonin (5-HT) in these cells. Conversely, this trend of decreasing % cAMP levels with increasing serotonin (5-HT) is not observed in cells lacking expression of 5-HT_(1A) receptor. 5-HT_(1A) receptor binding evaluation for compound with formula C(V) (designated simply “C-V” along the x-axis) is shown in FIG. 3L. Comparison of data acquired in +5-HT_(1A) cultures with those acquired in −5-HT_(1A) cultures suggests mild receptor modulation at higher ligand concentrations.

In Vitro Metabolic Stability Assays Using Intestinal Fractions, Liver Fractions, Serum Fractions, Alkaline Phosphatase Buffer, Esterase Buffer, and Control Buffer.

A fundamental evaluation in drug development is the assessment of absorption, distribution, metabolism, excretion, and pharmacokinetics (ADME/PK) (Eddershaw et al., 2000, Drug Discovery Today 5(9): 409-414). The first ADME screen that a novel chemical entity is subjected to is an in vitro metabolic stability screen (Ackley et al., 2004, Methods in Pharmacology and Toxicology Optimization in Drug Discovery (in vitro methods), Yan Z, Caldwell G. W. Eds; Humana Press Inc, New Jersey, pp. 151-164). Drug stability upon exposure to human liver microsomes and liver S9 cellular fractions is a common in vitro assay to approximate in vivo, liver-based drug metabolism (Richardson et al., 2016 Drug Metabolism Letters 10:83-90). First-pass metabolism is also often approximated in vitro using intestinal microsome and cellular S9 fractions (Hatley et al., 2017, Biopharmaceuticals & Drug Disposition, 38(2):155-160). Further, it is well known that human serum, and particularly circulating serum esterases can contribute to systemic drug metabolism (Williams, F M 1987, Pharmacology and Therapeutics, 34:99-109). Many pharmacological agents are classified as prodrugs, as they undergo metabolic transformation in vivo upon administration to release the active drug compound into the systemic compartment (Zawilska J B, et al. 2013, Pharmacological Reports, 65:1-14). Psilocybin, a serotonergic psychedelic agent, is well known prodrug that is metabolized into the psychoactive product, psilocin (Dinis-Oliveira, R J 2017, Drug Metabolism Reviews, 49(1):84-91). To evaluate the capacity of test molecules to similarly serve as prodrugs of psilocin, time-dependent, metabolic stability assays using human AB serum, human intestinal microsomes (HIM), human intestinal S9 fractions (HIS9), human liver microsomes (HLM), human liver S9 fractions (HLS9), human alkaline phosphatase, and porcine esterase were performed. Assays in enzyme-free buffer were also performed for control purposes, and for general assessment of compound stability. Liquid chromatography coupled mass spectrometry (LC-MS) was employed to track the conversion of the test molecules into psilocin. All intestinal and liver fractions and NADPH RapidStart reagent was purchased from Sekisui/XenoTech. Human AB serum was purchased from Sigma. For intestine and liver metabolism assays, 2.5 μM candidate compounds were incubated in 400 pg/ml of each cellular fraction (HLM, HLS9, HIM, or HIS9) in 50 mM potassium phosphate buffer (pH 7.4) containing 3 mM MgCl2 and 1 mM EDTA supplemented with NADPH RapidStart at 37° C. Samples were taken at the start of the assay, and at every 20 minutes for 2 hours. Time-point samples were precipitated with 1:1 volume of acetonitrile to quench the reaction before 76entrifugeation at 4000×g for 20 minutes. Supernatants were analyzed for the presence of candidate prodrugs (parent molecule) and psilocin (the predicted metabolite) using Orbitrap LC-MS (Thermo Scientific) using previously described methods (Menendez-Perdomo et al., 2021, J Mass Spectrom, 56: e4683). The serum assays were carried out in 10% human AB serum in 50 mM potassium phosphate buffer (pH 7.4) containing 3 mM MgCl₂ and 1 mM EDTA. Bovine alkaline phosphatase assays were carried out using one unit of enzyme in 50 mM potassium phosphate buffer (pH 7.4) containing 3 mM MgCl₂ and 1 mM EDTA. Porcine esterase assays were carried out using one unit of purified enzyme in 50 mM potassium phosphate buffer (pH 7.4) containing 3 mM MgCl₂ in 1 mM EDTA. Assay concentrations (M) of both parent ‘prodrug’ molecule and psilocin metabolite, as quantified through LC-MS using routine standard curve procedures, were plotted as functions of assay time (minutes). The metabolism rate (T_(1/2)) was determined from the metabolism curve plot using the one phase decay feature of GraphPad PRISM software (Version 9.2.0). The quantity of parent prodrug at time zero was set as 100%.

Positive controls were first tested to ensure that assays were functioning properly. Psilocybin is known to be metabolized to psilocin in the intestine and through alkaline phosphatase (Dinis-Oliveira, 2017 Drug Metab Rev 49: 84-91) and thus served as a positive control for HIM, HIS9 and alkaline phosphatase assays. Procaine is known to be metabolized to 4-amino benzoic acid in serum, liver, and through esterase (Henrikus and Kampffmeyer, 1992, Xenobiotica 22: 1357-1366) and thus served as a positive control for AB serum, HLM and esterase assays. Verapamil is known to be metabolized into a variety of metabolites in liver (Hanada et al., 2008, Drug Metab Dispos 36: 2037-2042) (catabolites not examined in this study) and thus served as an additional control for HLS9 and HLM assays.

FIGS. 3M (i)-3M (iii) illustrate results of ‘psilocin-release’ metabolic conversion assays using psilocybin as the parent prodrug control for HIM (Panel C), HIS9 (Panel D) and alkaline phosphatase (Panel E) assays. For context, psilocybin was further submitted to negative control buffer assay (Panel A), AB serum (Panel B), HLM (Panel F), and HLS9 (Panel G) assays. Notably, these plots demonstrate psilocybin is stable in liver fractions with no conversion to psilocin. Further, the stability of psilocybin was confirmed in assay buffer, confirming that transformation of this molecule is due to enzymes within the cellular fractions rather than due to buffer components. Finally, these results demonstrate psilocybin is stable in serum with no conversion to psilocin. FIGS. 3N (i)-3N (ii) illustrate results of additional controls for assay verification: procaine and AB serum (Panel A); procaine and HLM (Panel B); verapamil and HLS9 (Panel C); procaine and esterase (Panel D); verapamil and HLM (Panel E). FIGS. 3O (i)-3O (iii) show the metabolic stability curves for compound with formula C(V), designated “C-V,” in control buffer (Panel A), AB serum (Panel B), HIM (Panel C), HLM (Panel D), HIS9 (Panel E), HLS9 (Panel F), alkaline phosphatase (Panel G), and esterase (Panel H).

In Vivo Evaluation of 5-HT_(2A) Receptor Agonism in Mice.

Drug-induced Head Twitch Response (HTR), a rapid, involuntary movement of the mouse's head with little or no involvement of the trunk, is an established in vivo model behavior used to measure neuronal 5-HT_(2A) receptor (5-HT2AR) activation by established and novel hallucinogenic compounds (Canal and Morgan 2012, Drug Testing Analysis, 4:556-576). Indeed, HTR is widely utilized as a behavioral proxy in mice and rats to predict human hallucinogenic potential and can reliably differentiate between hallucinogenic and non-hallucinogenic 5-HT2AR agonists (Halberstadt and Geyer 2013, Psychopharmacology 227: 727-739; Gonzalez-Maeso et al., 2007, Neuron 53:439-452). To evaluate 5-HT2AR agonisms in vivo, HTR was measured in mice treated with a control and test compounds over a fixed window of time post-administration. All experiments were approved by the University of Calgary Animal Care and Use Committee in accordance with Canadian Council on Animal Care guidelines. Briefly, 8-week old C57BL/6-Elite male and female mice were obtained from Charles River. Prior to compound administration, all mice were group-housed, then single-housed on a 12:12 h light/dark schedule (lights on at 07:00 hours) with ad libitum access to food and water. Before any behavioral screening, mice were handled and exposed to the testing chamber for at least 5 min each day for three successive days and habituated to the experimental room 1 h before testing. The testing chamber was cleaned with a 70% ethanol solution between experiments. Control and test compounds, which were prepared at stock concentrations of 100 mM in DMSO, were diluted in sterile saline solution (0.9% NaCl). The sterile saline solution without control or test compounds (i.e., 0.9% NaCl) was dosed with 100 mM DMSO to create equivalent ‘vehicle’ solution. Prior to drug administration, mice were video monitored for 30 minutes in a plexiglass testing chamber (25.5×12.5×12.5 cm [L×W×H]) to allow for acclimation to the testing environment and to examine pre-drug spontaneous HTRs. After 30 minutes, compounds were administered via intraperitoneal (i.p.) injection at 1 mg/kg and mice were video monitored for 30 minutes then returned to their home cage. HTR analysis was conducted by an individual blinded to the subject treatment group using Behavioral Observation Research Interactive Software (BORIS, version 7, DOI: 10.1111/2041-210X.12584). Pre-drug behavior was examined during the 15-to-30-minute window prior to drug administration. Post-drug behavior was analyzed during the 15-to-30-minute window following drug administration. HTR associated with i.p. administration of psilocybin or vehicle were included as positive or negative control measures, respectively. Elevated incidences of HTR within the defined period of monitoring was observed in (1) psilocybin-treated mice, and (2) those treated with compound “C-V,” relative to control mice treated with i.p. injected vehicle. These results are illustrated in FIG. 3P, wherein vehicle is designated “veh,” psilocybin is designated “PCB,” compound with formula C(V) is designated “C-V,” pre-drug data is designated “pre-”, and post-drug data is designated “pro-.” Each replicate mouse is shown as a black dot along the corresponding vertical bars (N=2-6 per compound).

Mouse Pharmacokinetic (PK) Evaluation of Drug Metabolism to Psilocin.

Prodrugs are molecules with little or no pharmacological activity in their own right but have a built in structural lability, whether by chance or by design, that permits bioconversion in vivo. Psilocybin was recognized as a natural prodrug of the active agent psilocin shortly after the identification and chemical synthesis of the former compound in 1957 (Coppola et al., 2022 J Xenobiot 12: 41-52).

To further explore the potential of novel C₄-carboxylic acid-substituted tryptamine derivatives for use as psilocin prodrugs, a mouse PK study was performed. The aim of this study was to evaluate the time-dependent, in vivo conversion of novel derivative (“parent molecule”) to active psilocin metabolite. Specifically, the study was conducted using both PO (per os, by mouth) and IV (intravenous) dosing. Briefly, the procedure was as follows. For every compound (i.e., parent molecule), N=12 male C57Bl/6 mice were administered a single IV does (1 mg/kg) or a single oral dose (1, 3, or 10 mg/kg), with N=3 mice per dose group. Serial blood sampling via tail snip was performed at 8 time points up to 24 hours post-dosing. Samples were collected in K₂EDTA tubes, plasma was separated, and all samples were frozen until bioanalysis for parent compound and psilocin metabolite. Psilocybin was also assessed as a parent compound using this same protocol to establish a control benchmark PK profile. LC-MS/MS methodology was developed for (1) each parent compound, and (2) psilocin metabolite, using a 6-8 point calibration curve in singlet (75% of standards within +/−25% accuracy (+/−25% LLOQ)). Sample processing and analysis included 96 plasma and 4 dosing solutions per compound, with two calibration curves bracketing the sample batch. Nominal analyte concentrations were calculated for dosing solutions based on the quantity of weighed analyte dissolved in exact volume of dosing solution. However, to account for any analyte instability or other confounding factors, dosing solutions were sampled by LC-MS immediately prior to animal administration to obtain “measured” analyte quantity. Measured dose was considered the same as nominal dose when the formulation concentration was within 20% of nominal concentration. However, if the measured dose was outside this window, this new “measured” dose was used in all calculations. Each mouse was designated its own number (e.g., M01, M02 . . . ). Calculated values were as follows: T_(max) is the time at which maximum analyte concentration was observed; C_(max) is the maximum observed concentration; Apparent t_(1/2) is the apparent terminal half-life; AUC_(0-tlast) is the area under the “concentration versus time curve” from time zero to the time of the last measurable concentration; AUC_(0-inf) is the area under the “concentration versus time curve” from time zero to infinity; MRT_(0-inf) is the mean residence time from time zero to infinity; V_(ss) is the steady-state volume of distribution; F (%) is bioavailability=(Dose^(iv)*AUC^(po))/(Dose^(po)*AUC^(iv))*100. A further detailed description of the methodoly that was used to perform the foregoing mouse PK study can be found at: https://intervivo.com/pk-safety-studies/#pk-bridge; accessed Jul. 19, 2022.

Results for psilocybin PK following psilocybin administration are found in Tables 1A-1B, and FIG. 3Q. Notably, psilocybin was only detectable in i.v. administered animals; conversely, it was not detectable in orally administered animals at any dose, suggesting a degree of instability and/or quick conversion to psilocin. Results for psilocin PK following psilocybin administration are found in Tables 2A-2B (1 mg/kg IV dose), Tables 3A-3B (1 mg/kg oral dose), Tables 4A-4B (3 mg/kg oral dose), Tables 5A, B (10 mg/kg oral dose), Table 6 (psilocin exposure) and FIG. 3R.

TABLE 1A Plasma concentrations of psilocybin following 1 mg/kg i.v. administration of psilocybin. Experimental Plasma concentration (ng/mL) time (h) M01 M02 M03 Mean ± SD 0.0833 19.7 76.8 334 144 ± 167 0.25 3.32 8.95 27.2 13.2 ± 12.5 0.5 No Peak 2.35 6.21 4.28 (n = 2) 1 No Peak No Peak 1.21 1.21 (n = 1) 2 No Peak No Peak No Peak n/a 4 No Peak No Peak No Peak n/a 6 No Peak No Peak No Peak n/a 8 No Peak No Peak 2.54 n/a n/a denotes not applicable. Bolded value was considered an outlier and not included in calculations.

TABLE 1B Summary of plasma PK parameters for psilocybin following 1 mg/kg i.v. administration of psilocybin. Parameter estimate for each animal Parameter M01 M02 M03 Mean ± SD t_(max) (h) 0.0833 0.0833 0.0833 0.0833 ± 0.00  C_(max) (ng/mL) 19.7 76.8 334 144 ± 167

TABLE 2A Plasma concentrations of psilocin following 1 mg/kg i.v. administration of psilocybin. Experimental Plasma concentration (ng/mL) time (h) M01 M02 M03 Mean ± SD 0.0833 76.5 106 124  102 ± 24.0 0.25 84.5 61.3 73.5 73.1 ± 11.6 0.5 43.6 43.5 62.4 49.8 ± 10.9 1 36.7 25.5 20.5 27.6 ± 8.30 2 5.16 26.9 3.16 11.7 ± 13.2 4 1.98 5.36 1.70 3.01 ± 2.04 6 4.33 2.01 0.810 2.38 ± 1.79 8 0.439 0.250 1.32 0.670 ± 0.571

TABLE 2B Summary of plasma PK parameters for psilocin, following 1 mg/kg i.v. administration of psilocybin^(a). Parameter estimate for each animal Parameter M01 M02 M03 Mean ± SD t_(max) (h) 0.250 0.0833 0.0833  0.139 ± 0.0962 C_(max) (ng/mL) 84.5 106 124  105 ± 19.8 C_(max)/Dose^(a) 84.5 106 124  105 ± 19.8 (kg*ng/mL/mg) Apparent t_(1/2) (h) nc^(b) 0.905 nc 0.905 (n = 1) AUC_(0-tlast) (h*ng/mL) 84.5 109 75.5 89.8 ± 17.5 AUC_(0-tlast)/Dose^(a) 84.5 109 75.5 89.8 ± 17.5 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) n/a^(c) 110 n/a   110 (n = 1) MRT_(0-inf) (h) n/a  1.64 n/a  1.64 (n = 1) ^(a)Psilocybin dose was used. ^(b)nc denotes not calculable as the terminal phase is not well defined. ^(c)n/a denotes not applicable.

TABLE 3A Plasma concentrations of psilocin following 1.56 mg/kg oral administration of psilocybin. Experimental Plasma concentration (ng/mL) time (h) M04 M05 M06 Mean ± SD  0.25 50.2 53.8 29.6 44.5 ± 13.1  0.5 40.5 52.5 57.2 50.1 ± 8.61  1 26.8 31.2 37.9 32.0 ± 5.59  2 11.3 7.04 7.50 8.61 ± 2.34  4 1.64 1.86 1.25  1.58 ± 0.309  6 0.445 1.05 0.611 0.702 ± 0.313  8 1.24 0.511 0.738 0.830 ± 0.373 24 BLQ BLQ BLQ n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). n/a denotes not applicable.

TABLE 3B Summary of plasma PK parameters for psilocin, following 1.56 mg/kg oral administration of psilocybin^(a). Parameter estimate for each animal Parameter M04 M05 M06 Mean ± SD t_(max) (h) 0.250 0.250 0.500 0.333 ± 0.144 C_(max) (ng/mL) 50.2 53.8 57.2 53.7 ± 3.50 C_(max)/Dose^(a) (kg*ng/mL/mg) 32.2 34.5 36.7 34.4 ± 2.24 Apparent t_(1/2) (h) nc^(b) 2.15^(c) nc 2.15 (n = 1) AUC_(0-tlast) (h*ng/mL) 65.6 68.8 66.9 67.1 ± 1.61 AUC_(0-tlast)/Dose^(a) 42.1 44.1 42.9 43.0 ± 1.03 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) n/a^(d) 70.4 n/a 70.4 (n = 1) MRT₀._(inf) (h) n/a  1.53 n/a 1.53 (n = 1) ^(a)Administered dose of psilocybin (1.56 mg/kg) was used. ^(b)nc denotes not calculable as the terminal phase is not well defined. ^(c)Apparent t_(1/2) estimate may not be accurate; sampling interval during the terminal phase <2 × t_(1/2). ^(d)n/a denotes not applicable.

TABLE 4A Plasma concentrations of psilocin following 3 mg/kg oral administration of psilocybin. Experimental Plasma concentration (ng/mL) time (h) M07 M08 M09 Mean ± SD  0.25 52.6 53.0 41.5 49.0 ± 6.53  0.5 55.3 62.0 35.0 50.8 ± 14.1  1 23.2 35.5 36.2 31.6 ± 7.31  2 13.1 10.5 23.2 15.6 ± 6.71  4 2.28 1.93 3.16  2.46 ± 0.634  6 1.43 1.04 1.79  1.42 ± 0.375  8 0.734 0.368 0.493 0.532 ± 0.186 24 BLQ 0.111 0.402 0.257 (n = 2) BLQ denotes below the lower limit of quantitation (0.2 ng/mL). Value in italics is below the lower limit of quantitation (BLQ, 0.2 ng/mL) but was included in calculations.

TABLE 4B Summary of plasma PK parameters for psilocin, following 3 mg/kg oral administration of psilocybin^(a). Parameter estimate for each animal Parameter M07 M08 M09 Mean ± SD t_(max) (h) 0.500 0.500 0.250 0.417 ± 0.144 C_(max) (ng/mL) 55.3 62.0 41.5 52.9 ± 10.5 C_(max)/Dose^(a) (kg*ng/mL/mg) 18.4 20.7 13.8 17.6 ± 3.48 Apparent t_(1/2) (h)^(b) 2.45 6.58 nc^(c) 4.51 (n = 2) AUC_(0-tlast) (h*ng/mL) 74.3 83.0 95.8 84.4 ± 10.8 AUC_(0-tlast)/Dose^(a) 24.8 27.7 31.9 28.1 ± 3.61 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 76.9 84.1 n/a^(d) 80.5 (n = 2) MRT_(0-inf) (h) 1.84 2.24 n/a  2.04 (n = 2) ^(a)Psilocybin dose was used. ^(b)For M07, apparent t_(1/2) estimate may not be accurate; sampling interval during the terminal phase <2 × t_(1/2). ^(c)nc denotes not calculable as the terminal phase is not well defined. ^(d)n/a denotes not applicable.

TABLE 5A Plasma concentrations of psilocin following 10 mg/kg oral administration of psilocybin. Experimental Plasma concentration (ng/mL) time (h) M10 M11 M12 Mean ± SD  0.25 238 234 202  225 ± 19.7  0.5 202 289 156  216 ± 67.5  1 145 156 166  156 ± 10.5  2 53.9 54.7 66.6 58.4 ± 7.11  4 8.32 23.5 10.2 14.0 ± 8.28  6 3.51 16.8 10.3 10.2 ± 6.65  8 3.13 5.18 7.06 5.12 ± 1.97 24 0.258 0.201 0.186  0.215 ± 0.0380 BLQ denotes below the lower limit of quantitation (0.2 ng/mL). Value in italics is below the lower limit of quantitation (BLQ, 0.2 ng/mL) but was included in calculations.

TABLE 5B Summary of plasma PK parameters for psilocin following 10 mg/kg oral administration of psilocybin^(a). Parameter estimate for each animal Parameter M10 M11 M12 Mean ± SD t_(max) (h) 0.250 0.500 0.250 0.333 ± 0.144 C_(max) (ng/mL) 238 289 202  243 ± 43.7 C_(max)/Dose^(a) 23.8 28.9 20.2 24.3 ± 4.37 (kg*ng/mL/mg) Apparent t_(1/2) (h) 4.64 3.02 3.09  3.58 ± 0.920 AUC_(0-tlast) (h*ng/mL) 348 457 387  397 ± 55.5 AUC_(0-tlast)/Dose^(a) 34.8 45.7 38.7 39.7 ± 5.55 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 349 458 388  398 ± 55.1 MRT_(0-inf) (h) 2.14 2.44 2.60  2.39 ± 0.236 ^(a)Psilocybin dose was used.

TABLE 6 Summary of mean plasma exposure of psilocin as a function of psilocybin dose. Psilocybin dose Parameter 1 mg/kg i.v. 1.56 mg/kg p.o. 3 mg/kg p.o. 10 mg/kg p.o. C_(max)/Dose^(a) (kg*ng/mL/mg)  105 ± 19.8 34.4 ± 2.24 17.6 ± 3.48 24.3 ± 4.37 Apparent t_(1/2) (h) 0.905 (n = 1) 2.15 (n = 1) 4.51 (n = 2)  3.58 ± 0.920 AUC_(0-tlast)/Dose^(a) 89.8 ± 17.5 43.0 ± 1.03 28.1 ± 3.61 39.7 ± 5.55 (h*kg*ng/mL/mg)

Results for compound C(V) PK following C(V) administration are found in Tables 7A and 7B. Notably, compound C(V) was only detectable in iv. administered animals; conversely, it was not detectable in orally administered animals at any dose, suggesting a degree of instability and/or quick conversion to psilocin. Furthermore, C(V) was determined to be unstable in plasma (see notes in Table 7A and 7B) thus rendering LC-MS-determined quantities inaccurate.

TABLE 7A Plasma concentrations of C(V) following 1 mg/kg i.v. administration of C(V). Experimental Plasma concentration (ng/mL)^(a) time (h) M13 M14 M15 Mean ± SD 0.0833 6.53 53.8 13.5 24.6 ± 25.5 0.25 0.834 BLQ BLQ 0.834 (n = 1) 0.5 BLQ No Peak No Peak n/a 1 No Peak No Peak No Peak n/a 2 No Peak No Peak No Peak n/a 4 No Peak No Peak No Peak n/a 6 No Peak No Peak No Peak n/a 8 No Peak No Peak No Peak n/a ^(a)A freshly spiked calibration curve was used for quantification C(V) is not stable in plasma; concentrations are not considered accurate. BLQ denotes below the lower limit of quantitation (0.5 ng/mL). n/a denotes not applicable.

TABLE 7B Summary of plasma PK parameters for C(V) following 1 mg/kg i.v. administration of C(V). Parameter estimate for each animal Parameter^(a) M13 M14 M15 Mean ± SD t_(max) (h) 0.0833 0.0833 0.0833 0.0833 ± 0.00  C_(max) (ng/mL) 6.53 53.8 13.5 24.6 ± 25.5 ^(a)Due to C(V) instability in plasma, the PK parameter estimates are not considered accurate.

Results for psilocin PK following C(V) administration are found in Tables 8A-8B (1 mg/kg IV dose), Tables 9A-9B (1 mg/kg oral dose), Tables 10A-10B (3 mg/kg oral dose), Tables 11A-11B (10 mg/kg oral dose), Table 12 (comparative summary for IV data), Table 13 (comparative summary for oral data), Table 14A (psilocin exposure) and FIGS. 3S (i) and 3S (ii).

TABLE 8A Plasma concentrations of psilocin following 1 mg/kg i.v. administration of C(V). Experimental Plasma concentration (ng/mL) time (h) M13 M14 M15 Mean ± SD 0.0833 59.4 210 119  129 ± 75.8 0.25 34.7 24.4 39.5 32.9 ± 7.72 0.5 15.7 22.5 19.8 19.3 ± 3.42 1 5.27 8.27 6.72 6.75 ± 1.50 2 1.57 1.74 1.26  1.52 ± 0.243 4 0.321 1.33 0.941 0.864 ± 0.509 6 0.197 0.470 1.91 0.859 ± 0.920 8 BLQ 0.241 0.102 0.172 (n = 2) BLQ denotes below the lower limit of quantitation (0.2 ng/mL). Values in italics are below the lower limit of quantitation (BLQ, 0.2 ng/mL) but were included in calculations.

TABLE 8B Summary of plasma PK parameters for psilocin following 1 mg/kg i.v. administration of C(V)^(a). Parameter estimate for each animal Parameter M13 M14 M15 Mean ± SD t_(max) (h) 0.0833 0.0833 0.0833 0.0833 ± 0.00  C_(max) (ng/mL) 59.4 210 119  129 ± 75.8 C_(max)/Dose^(a) 59.4 210 119  129 ± 75.8 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.06 1.62 nc^(b)  1.34 (n = 2) AUC_(0-tlast) (h*ng/mL) 26.0 45.7 39.7 37.1 ± 10.1 AUC_(0-tlast)/Dose^(a) 26.0 45.7 39.7 37.1 ± 10.1 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 26.4 46.2 n/a^(c)  36.3 (n = 2) MRT_(0-inf) (h) 0.797 0.936 n/a  0.867 (n = 2) ^(a)C(V) dose was used. ^(b)nc denotes not calculable as the terminal phase is not well defined. ^(c)n/a denotes not applicable.

TABLE 9A Plasma concentrations of psilocin following 1 mg/kg oral administration of C(V). Experimental Plasma concentration (ng/mL) time (h) M16 M17 M18 Mean ± SD  0.25 7.58 8.33 10.2 8.70 ± 1.35  0.5 8.91 5.76 8.34 7.67 ± 1.68  1 4.03 3.32 4.74  4.03 ± 0.710  2 1.65 0.88 1.28  1.27 ± 0.385  4 0.525 0.379 0.770 0.558 ± 0.198  6 0.154 0.147 0.144  0.148 ± 0.00513  8 0.123 BLQ 0.225 0.174 (n = 2) 24 No Peak BLQ BLQ n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). Values in italics are below the lower limit of quantitation (BLQ, 0.2 ng/mL) but were included in calculations. n/a denotes not applicable.

TABLE 9B Summary of plasma PK parameters for psilocin following 1 mg/kg oral administration of C(V)^(a). Parameter estimate for each animal Parameter M16 M17 M18 Mean ± SD t_(max) (h) 0.500 0.250 0.250 0.333 ± 0.144 C_(max) (ng/mL) 8.91 8.33 10.2  9.15 ± 0.957 C_(max)/Dose^(a) 8.91 8.33 10.2  9.15 ± 0.957 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.54 1.55 nc^(b) 1.54 (n = 2) AUC_(0-tlast) (h*ng/mL) 11.6 8.51 12.5 10.9 ± 2.10 AUC_(0-tlast)/Dose^(a) 11.6 8.51 12.5 10.9 ± 2.10 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 11.9 8.84 n/a^(c) 10.4 (n = 2) MRT_(0-inf) (h) 1.70 1.53 n/a  1.62 (n = 2) ^(a)C(V) dose was used. ^(b)nc denotes not calculable as the terminal phase is not well defined. ^(c)n/a denotes not applicable.

TABLE 10A Plasma concentrations of psilocin following 3 mg/kg oral administration of C(V). Experimental Plasma concentration (ng/mL) time (h) M19 M20 M21 Mean ± SD  0.25 26.1 21.7 34.2 27.3 ± 6.34  0.5 26.4 25.0 23.6 25.0 ± 1.40  1 15.5 17.2 14.5 15.7 ± 1.37  2 5.46 3.54 3.86 4.29 ± 1.03  4 1.07 0.836 0.507 0.804 ± 0.283  6 0.634 0.446 0.374 0.485 ± 0.134  8 0.359 0.116 0.203 0.226 ± 0.123 24 No Peak BLQ BLQ n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). Value in italics is below the lower limit of quantitation (BLQ, 0.2 ng/mL) but was included in calculations. n/a denotes not applicable.

TABLE 10B Summary of plasma PK parameters for psilocin following 3 mg/kg oral administration of C(V). Parameter estimate for each animal Parameter M19 M20 M21 Mean ± SD t_(max) (h) 0.500 0.500 0.250 0.417 ± 0.144 C_(max) (ng/mL) 26.4 25.0 34.2 28.5 ± 4.96 C_(max)/Dose^(a) 8.80 8.33 11.4 9.51 ± 1.65 (kg*ng/mL/mg) Apparent t_(1/2) (h)^(b) 2.54 1.40 3.03  2.32 ± 0.834 AUC_(0-tlast) (h*ng/mL) 37.7 33.1 33.5 34.8 ± 2.54 AUC_(0-tlast)/Dose^(a) 12.6 11.0 11.2  11.6 ± 0.847 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 39.0 33.3 34.4 35.6 ± 3.02 AUC_(0-inf)/Dose^(a) 13.0 11.1 11.5 11.9 ± 1.01 (h*kg*ng/mL/mg) MRT_(0-inf) (h) 1.78 1.34 1.44  1.52 ± 0.229 ^(a)C(V) dose was used. ^(b)For M19 and M21, apparent t_(1/2) estimate may not be accurate; sampling interval during the terminal phase <2 × t_(1/2).

TABLE 11A Plasma concentrations of psilocin following 10 mg/kg oral administration of C(V). Experimental Plasma concentration (ng/mL) time (h) M22 M23 M24 Mean ± SD  0.25 42.1 76.7 103 73.9 ± 30.5  0.5 54.8 78.8 55.3 63.0 ± 13.7  1 36.1 42.0 26.5 34.9 ± 7.82  2 17.3 22.4 16.6 18.8 ± 3.17  4 8.72 3.48 3.01 5.07 ± 3.17  6 4.06 7.23 2.29 4.53 ± 2.50  8 1.41 2.51 3.87 2.60 ± 1.23 24 BLQ BLQ No Peak n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). n/a denotes not applicable.

TABLE 11B Summary of plasma PK parameters for psilocin following 10 mg/kg oral administration of C(V)^(a). Parameter estimate for each animal Parameter M22 M23 M24 Mean ± SD t_(max) (h) 0.500 0.500 0.250 0.417 ± 0.144 C_(max) (ng/mL) 54.8 78.8 103 78.9 ± 24.1 C_(max)/Dose^(a) 5.48 7.88 10.3 7.89 ± 2.41 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.52 nc^(b) nc 1.52 (n = 1) AUC_(0-tlast) 108 129 100  112 ± 15.2 (h*ng/mL) AUC_(0-tlast)/Dose^(a) 10.8 12.9 10.0 11.2 ± 1.52 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 111 n/a^(c) n/a  111 (n = 1) MRT_(0-inf) (h) 2.32 n/a  n/a 2.32 (n = 1) ^(a)C(V) dose was used. ^(b)nc denotes not calculable as the terminal phase is not well defined. ^(c)n/a denotes not applicable.

TABLE 12 Comparative summary of psilocin pharmacokinetic (PK) parameters following intravenous (IV) dosing of psilocybin or compound C(V). Parameter Psilocybin C(V) Prodrug nominal dose (mg/kg) 1 1 Prodrug measured dose (mg/kg)^(a) 1 1 t_(max) (h)  0.139 ± 0.0962 0.0833 ± 0.00  C_(max) (ng/mL)  105 ± 19.8  129 ± 75.8 C_(max)/Dose^(b) _(nominal) (kg*ng/mL/mg)  105 ± 19.8  129 ± 75.8 C_(max)/Dose^(b) _(measured) (kg*ng/mL/mg)  105 ± 19.8  129 ± 75.8 Apparent t_(1/2) (h) 0.905 (n = 1)  1.34 (n = 2) AUC_(0-tlast) (h*ng/mL) 89.8 ± 17.5 37.1 ± 10.1 AUC_(0-tlast)/Dose^(b) _(nominal) 89.8 ± 17.5 37.1 ± 10.1 (h*kg*ng/mL/mg) AUC_(0-tlast)/Dose^(b) _(measured) 89.8 ± 17.5 37.1 ± 10.1 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL)   110 (n = 1)  36.3 (n = 2) MRT_(0-inf) (h)  1.64 (n = 1) 0.867 (n = 2) ^(a)Measured dose is the same as nominal dose when the formulation concentration was within 20% of nominal concentration ^(b)Prodrug dose was used

TABLE 13 Comparative summary of psilocin pharmacokinetic (PK) parameters following oral (PO) dosing of psilocybin or compound C(V). Parameter Psilocybin C(V) Prodrug nominal dose (mg/kg) 1 3 10 1 3 10 Prodrug measured dose (mg/kg)^(a) 1.56 3 10 1 3 10 t_(max) (h) 0.333 ± 0.144 0.417 ± 0.144 0.333 ± 0.144 0.333 ± 0.144 0.417 ± 0.144 0.417 ± 0.144 C_(max) (ng/mL) 53.7 ± 3.50 52.9 ± 10.5  243 ± 43.7  9.15 ± 0.957 28.5 ± 4.96 78.9 ± 24.1 C_(max)/Dose^(b) _(nominal) 1.56 17.6 ± 3.48 24.3 ± 4.37 1 9.51 ± 1.65 7.89 ± 2.41 (kg*ng/mL/mg) C_(max)/Dose^(b) _(measured) 34.4 ± 2.24 17.6 ± 3.48 24.3 ± 4.37  9.15 ± 0.957 9.51 ± 1.65 7.89 ± 2.41 (kg*ng/mL/mg) Apparent t_(1/2) (h) 2.15 (n = 1) 4.51 (n = 2)  3.58 ± 0.920 1.54 (n = 2)  2.32 ± 0.834 1.52 (n = 1) AUC_(0-tlast) (h*ng/mL) 67.1 ± 1.61 84.4 ± 10.8  397 ± 55.5 10.9 ± 2.10 34.8 ± 2.54  112 ± 15.2 AUC_(0-tlast)/Dose^(b) _(nominal) 34.4 ± 2.24 28.1 ± 3.61 39.7 ± 5.55  9.15 ± 0.957  11.6 ± 0.847 11.2 ± 1.52 (h*kg*ng/mL/mg) AUC_(0-tlast)/Dose^(b) _(measured) 43.0 ± 1.03 28.1 ± 3.61 39.7 ± 5.55 10.9 ± 2.10  11.6 ± 0.847 11.2 ± 1.52 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 70.4 (n = 1) 80.5 (n = 2)  398 ± 55.1 10.4 (n = 2) 35.6 ± 3.02 111 (n = 1) MRT_(0-inf) (h) 1.53 (n = 1) 2.04 (n = 2)  2.39 ± 0.236 1.62 (n = 2)  1.52 ± 0.229 2.32 (n = 1) ^(a)Measured dose is the same as nominal dose when the formulation concentration was within 20% of nominal concentration. ^(c)nc denotes not calculable as % AUC extrapolated from tlast to infinity is >20%, thus estimate is not considered accurate. ^(d)n/a denotes not applicable.

TABLE 14A Summary of mean plasma exposure of psilocin as a function of C(V) dose. C(V) dose Parameter 1 mg/kg i.v. 1 mg/kg p.o. 3 mg/kg p.o. 10 mg/kg p.o. C_(max)/Dose^(a)  129 ± 75.8  9.15 ± 0.957 9.51 ± 1.65 7.89 ± 2.41 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.34 (n = 2) 1.54 (n = 2)  2.32 ± 0.834 1.52 (n = 1) AUC_(0-tlast)/Dose^(a) 37.1 ± 10.1 10.9 ± 2.10  11.6 ± 0.847 11.2 ± 1.52 (h*kg*ng/mL/mg)

In Vitro Survey of Pharmacological Interaction Profiles at Receptors, Transporters and Enzymes Linked to Targeted Health Conditions.

To expand pharmacological profiling to include a broader range of targets with known involvement in, or connection to, brain neurological disorders, compound C(V) was evaluated with respect to receptor interaction (https://www.eurofinsdiscoveryservices.com/). Specifically, the cell-based screening assay panel known as “SAFETYscan E/IC150 ELECT” was used to generate data regarding interaction of derivative molecules with 20 different proteins, including 12 GPCR receptors (ADRA1A, ADRA2A, AVPR1A, CHRM1, CHRM2, CNR1, DRD1, DRD2S, HTR1A (5-HT_(1A)), HTR1B (5-HTR1B), HTR2B (5-HT_(2B)), OPRD1), 3 ion channels (GABAA, HTR3A (5-HT_(3A)), NMDAR), one enzyme (MAO-A), and 3 transporters (DAT, NET, SERT).

i. EFC-Based cAMP Secondary Messenger Assay.

Of the 12 GPCR proteins, 8 were assayed via a cAMP secondary messenger assay: ADRA2A, CHRM2, CNR1, DRD1, DRD2S, HTR1A, HTR1B, OPRD1. Briefly, employed a panel of cell lines stably expressing non-tagged GPCR proteins that endogenously signal through cAMP. These assays monitored the activation of a GPCR through G_(i) or G_(s) secondary messenger signaling in a homogenous, non-imaging assay format using a technology termed EnzymeFragment Complementation (EFC). EFC uses p-galactosidase (p-gal) as the functional endpoint. The p-gal enzyme is split into two complementary portions: Enzyme Acceptor (EA) and Enzyme Donor (ED). In the assay, exogenously introduced ED fused to cAMP (ED-cAMP) competes with endogenously generated cAMP for binding to an anti-cAMP-specific antibody. Active p-gal is formed by complementation of exogenous EA to any unbound ED-cAMP. Active enzyme can then convert a chemiluminescent substrate, generating an output signal detectable on a standard microplate reader.

These 8 cAMP-based assays were conducted in both agonist and antagonist modes, either in G_(s) format (no forskolin) or in G_(i) format (in the presence of EC₈₀ forskolin). For G_(s) and G_(i) agonist assays: cell media was aspirated from GPCR-containing cultures and replaced with 15 μl 2:1HBSS/1-mM HEPES:cAMP XS+Ab reagent. Five microlitres of derivative compound, prepared as a stock solution (also containing EC₈₀ forskolin in the case of G_(i) format) were added to the cells at final target concentrations and pre-incubated for 30 minutes. Final assay vehicle concentration was 1%. After pre-incubation, assay signal was generated through the addition of (1) 20 μL cAMP XS+ED/CL lysis cocktail, and (2) 20 LcAMP XS+EA reagent, allowing incubation periods of one and three hours, respectively. Antagonist assays were performed in the same manner as agonist assays, except pre-incubation entailed exposure to the test derivative (30 minutes) followed by exposure to an established agonist at EC₈₀ (“agonist challenge”, 30 minutes). In the case of antagonist assays of G_(i)-coupled GPCRs, EC₈₀ forskolin was included in assay buffers.

In all 8 cAMP assays (agonist or antagonist mode), the resulting chemiluminescent signal was measured using a PerkinElmer Envision™ instrument. Compound activity was analyzed using CBIS data analysis suite (ChemInnovation, CA). Percent activity (%) was calculated according to standard procedures. For example: in G_(s) agonist mode assays, percentage activity was calculated using the following formula: % activity=100%×[mean RLU of test derivative−mean RLU of vehicle control]/[mean RLU of control ligand −mean RLU of vehicle control]. For G_(s) antagonist mode assays, percentage inhibition was calculated using the following formula: % inhibition=100%×[1−[mean RLU of test derivative−mean RLU of vehicle control]/[mean RLU of EC₈₀ control ligand −mean RLU of vehicle control]]. For G_(i) agonist mode assays, percentage activity was calculated using the following formula: % activity=100%×[1−[mean RLU of test derivative−mean RLU of control ligand]/[mean RLU of vehicle control−mean RLU of control ligand]]. For G_(i) antagonist or negative allosteric mode assays, percentage inhibition was calculated using the following formula: % inhibition=100%×[mean RLU of test compound−mean RLU of EC₈₀ control ligand]/[mean RLU of forskolin positive control−mean RLU of EC₈₀ control]. For primary screens, percent response was capped at 0% or 100% where calculated percent response returned a negative value or a value greater than 100, respectively. To assess assay performance and establish positive control benchmarks, ligands listed in Table 14B were evaluated alongside test derivatives. Results for EFC-based cAMP secondary messenger assays on GPCRs using compound C(V) ligand or positive controls are shown in Table 14C.

ii. Calcium Secondary Messenger Assay.

Of the 12 GPCR proteins, 4 were assayed via a calcium secondary messenger assay: ADRA1A, AVPR1A, CHRM1, HTR2B. Briefly, the Calcium No WashPLUS assay monitors GPCR activity via G_(q) secondary messenger signaling in a live cell, non-imaging assay format. Eurofins DiscoverX employed proprietary cell lines stably expressing G_(q)-coupled GPCR proteins. Calcium mobilization was monitored using a calcium-sensitive dye loaded into cells. GPCR activation by a test or control compound resulted in the release of calcium from intracellular stores and an increase in dye fluorescence that is measured in real-time.

The four GPCR proteins assayed via calcium secondary messenger assay were surveyed in both agonist and antagonist modes. Cell lines were expanded from freezer stocks according to standard procedures, seeded into microplates and incubated at 37° C. prior to testing. Assays were performed in 1× dye loading buffer consisting of 1× dye (DiscoverX, Calcium No WashPLUS kit, Catalog No. 90-0091), 1× Additive A and 2.5 mM probenecid in HBSS/20 mM Hepes. Cells were loaded with dye prior to testing. Media was aspirated from cells and replaced with 25 μL dye loading buffer, incubated for 45 minutes at 37° C. and then 20 minutes at room temperature. For agonist determination, cells were incubated with sample compound to induce response. After dye loading, cells were removed from the incubator and 25 μL of 2× compound in HBSS/20 mM Hepes was added using a FLIPR Tetra (MDS). Compound agonist activity was measured on a FLIPR Tetra. Calcium mobilization was monitored for 2 minutes with a 5 second baseline read. For antagonist determination, cells were pre-incubated with sample compound followed by agonist challenge at the EC₈₀ concentration. After dye loading, cells were removed from the incubator and 25 μL 2× sample compound was added. Cells were incubated for 30 minutes at room temperature in the dark to equilibrate plate temperature. After incubation, antagonist determination was initiated with addition of 25 μL 1× derivative compound with 3× EC₈₀ agonist using FLIPR. Compound antagonist activity was measured on a FLIPR Tetra (MDS). Calcium mobilization was monitored for 2 minutes with a 5 second baseline read. In both agonist and antagonist modes, data analysis was initiated using FLIPR, where area under the curve was calculated for the entire two minute read. Compound activity was analyzed using CBIS data analysis suite (ChemInnovation, CA). For agonist mode assays, percentage activity was calculated using the following formula: % activity=100%×[mean RFU of test compound−mean RFU of vehicle control]/[mean RFU control ligand −mean RFU of vehicle control]. For antagonist mode assays, percentage inhibition was calculated using the following formula: % inhibition=100%×[1−[mean RFU of test compound−mean RFU of vehicle control]/[mean RFU of EC₈₀ control−mean RFU of vehicle control]]. For primary screens, percent response was capped at 0% or 100%, where calculated percent response returned a negative value or a value greater than 100, respectively. To assess assay performance and establish positive control benchmarks, ligands listed in Table 14B were evaluated alongside test derivatives. Results for EFC-based cAMP secondary messenger assays on GPCRs using compound C(V) ligand or positive controls are shown in Table 14C.

iii. Ion Channel Assays.

Both ‘blocker’ and ‘opener’ activities of putative ligands on three distinct ion channels (GABAA, HTR3A, NMDAR) were surveyed. Briefly, Eurofins DiscoverX was employed in conjunction with the FLIPR Membrane Potential Assay Kit (Molecular Devices) which utilizes a proprietary fluorescent indicator dye in combination with a quencher to reflect real-time membrane potential changes associated with ionchannel activation and ion transporter proteins. Unlike traditional dyes such as DiBAC, the FLIPR Membrane Potential Assay Kit detects bidirectional ion fluxes so both variable and control conditions can be monitored within a single experiment. Cell lines were expanded from freezer stocks according to standard procedures, seeded onto microplates, and incubated at 37° C. Assays were performed in 1× Dye Loading Buffer consisting of 1× Dye and 2.5 mM probenecid when applicable. Cells were loaded with dye prior to testing and incubated for 30-60 minutes at 37° C. For agonist (‘Opener’) assays, cells were incubated with sample (i.e., containing derivative or control compound; Table 14B) to induce response as follows. Dilution of sample stocks was performed to generate 2-5× sample (i.e., containing derivative or control compound) in assay buffer. Next, 10-25 μL of 2-5× sample was added to cells and incubated at 37° C. or room temperature for 30 minutes. Antagonist (‘Blocker’) assays were performed using the same procedure except that after dye loading, cells were removed from the incubator and 10-25 μL 2-5× sample (i.e., containing derivative or control compound) was added to cells in the presence of EC₈₀ agonist. Cells were incubated for 30 minutes at room temperature in the dark to equilibrate plate temperature. Compound activity was measured on a FLIPR Tetra (Molecular Devices). Compound activity was analyzed using CBIS data analysis suite (ChemInnovation, CA). For agonist mode assays, percentage activity was calculated using the following formula: % activity=100%×[mean RLU of test derivative−mean RLU of vehicle control]/[mean control ligand −mean RLU of vehicle control]. For antagonist mode, percentage inhibition was calculated using the following formula: % inhibition=100%×[1−[mean RLU of test derivative−mean RLU of vehicle control]/[mean RLU of EC₈₀ control−mean RLU of vehicle control]]. For primary screens, percent response was capped at 0% or 100% where calculated percent response returned a negative value or a value greater than 100, respectively. To assess assay performance and establish positive control benchmarks, ligands listed in Table 14B were evaluated alongside test derivatives. Results for EFC-based cAMP secondary messenger assays on GPCRs using compound C(V) ligand or positive controls are shown in Table 14C.

iv. Neurotransmitter Transporter Uptake Assays.

The Neurotransmitter Transporter Uptake Assay Kit from Molecular Devices was used to examine impact of test compounds on 3 distinct transporters (DAT, NET, SERT). This kit provided a homogeneous fluorescence-based assay for the detection of dopamine, norepinephrine or serotonin transporter activity in cells expressing these transporters. The kit employed a fluorescent substrate that mimics the biogenic amine neurotransmitters that are taken into the cell through the specific transporters, resulting in increased intracellular fluorescence intensity. Cell lines were expanded from freezer stocks according to standard procedures, seeded into microplates and incubated at 37° C. prior to testing. Assays were performed in 1× Dye Loading Buffer consisting of 1× Dye, and 2.5 mM probenecid as applicable. Next, cells were loaded with dye and incubated for 30-60 minutes at 37° C. “Blocker” or antagonist format assays were performed, where cells were pre-incubated with sample (i.e., containing sample derivative or positive control compound) as follows. Dilution of sample stocks (i.e., containing sample derivative or positive control compound; Table 14B) was conducted to generate 2-5× sample in assay buffer. After dye loading, cells were removed from the incubator and 10-25 μL 2-5× sample (i.e., containing sample derivative or positive control compound) was added to cells in the presence of EC₈₀ agonist as appropriate. Cells were incubated for 30 minutes at room temperature in the dark to equilibrate plate temperature. Compound activity was measured on a FLIPR Tetra (Molecular Devices), and activity was analyzed using CBIS data analysis suite (ChemInnovation, CA). For antagonist (‘Blocker’) mode, percentage inhibition was calculated using the following formula: % inhibition=100%×[1−[mean RLU of test sample−mean RLU of vehicle control]/[mean RLU of EC₈₀ control−mean RLU of vehicle control]]. For primary screens, percent response was capped at 0% or 100% where calculated percent response returned a negative value or a value greater than 100, respectively. To assess assay performance and establish positive control benchmarks, ligands listed in Table 14B were evaluated alongside test derivative. Results for EFC-based cAMP secondary messenger assays on GPCRs using compound C(V) ligand or positive controls are shown in Table 14C.

v. MAO-A Enzyme Assay.

For the MAO-A assay, all chemicals and enzyme preparations were sourced from Sigma. Briefly, enzyme and test compound (i.e., derivative or control compound; see Table 14B) were preincubated for 15 minutes at 37° C. before substrate addition. The reaction was initiated by addition of kynuramine and incubated at 37° C. for 30 minutes. The reaction was terminated by addition of NaOH. The amount of 4-hydroquioline formed was determined through spectrofluorimetric readout with the emission detection at 380 nm and excitation wavelength 310 nm. For each assay, microplates were transferred to a PerkinElmer Envision™ instrument for readouts as per standard procedures. Compound activity was analyzed using CBIS data analysis suite (ChemInnovation, CA). Percentage inhibition was calculated using the following formula: % inhibition=100%×[1−[mean RLU of test sample−mean RLU of vehicle control]/[mean RLU of positive control−mean RLU of vehicle control]]. For primary screens, percent response was capped at 0% or 100% where calculated percent response returned a negative value or a value greater than 100, respectively. To assess assay performance and establish positive control benchmarks, ligands listed in Table 14B were evaluated alongside test derivative. Results for EFC-based cAMP secondary messenger assays on GPCRs using compound C(V) ligand or positive controls are shown in Table 14C.

TABLE 14B Control ligands used for target assays (GPCR, G-protein coupled receptor; IC, ion channel; EN, enzyme; TR, transporter). Target Assay Type Control ligand/modulator ADRA1A Agonist GPCR A 61603 Hydrobromide ADRA1A Antagonist GPCR Tamsulosin ADRA2A Agonist GPCR UK 14304 ADRA2A Antagonist GPCR Yohimbine AVPR1A Agonist GPCR [Arg8]-Vasopressin AVPR1A Antagonist GPCR SR 49059 CHRM1 Agonist GPCR Acetylcholine chloride CHRM1 Antagonist GPCR Atropine CHRM2 Agonist GPCR Acetylcholine chloride CHRM2 Antagonist GPCR Atropine CNR1 Agonist GPCR CP 55940 CNR1 Antagonist GPCR AM 251 DRD1 Agonist GPCR Dopamine DRD1 Antagonist GPCR SCH 39166 DRD2S Agonist GPCR Dopamine DRD2S Antagonist GPCR Risperidone HTR1A Agonist GPCR Serotonin hydrochloride HTR1A Antagonist GPCR Spiperone HTR1B Agonist GPCR Serotonin hydrochloride HTR1B Antagonist GPCR SB 224289 HTR2B Agonist GPCR Serotonin hydrochloride HTR2B Antagonist GPCR LY 272015 OPRD1 Agonist GPCR DADLE OPRD1 Antagonist GPCR Naltriben GABAA Opener IC GABA GABAA Blocker IC Picrotoxin HTR3A Opener IC Serotonin hydrochloride HTR3A Blocker IC Bemesetron MAO-A Inhibitor EN Clorgyline DAT Blocker TR GBR 12909 NET Blocker TR Desipramine SERT Blocker TR Clomipramine NMDAR Blocker IC (+)-MK 801 NMDAR Opener IC L-Glutamic acid

TABLE 14C Data summary table of target assays for compound C(V) and control ligands. Potency (EC₅₀ or IC₅₀) is provided in units of μM. AGN, agonist; ANT, antagonist; OP, opener; BL, blocker; IN, inhibitor. Target name Target type Assay type EC₅₀ (control) IC₅₀ (control) EC₅₀ (C-V) IC₅₀ (C-V) ADRA1A GPCR AGN 5.00E−05 — >100 — ADRA1A GPCR ANT — 9.60E−04 — 14.93 ADRA2A GPCR AGN 4.00E−05 — >100 — ADRA2A GPCR ANT — 3.10E−03 — >100 AVPR1A GPCR AGN 4.20E−04 — >100 — AVPR1A GPCR ANT — 1.60E−03 — >100 CHRM1 GPCR AGN 9.70E−03 — >100 — CHRM1 GPCR ANT — 6.10E−03 — >100 CHRM2 GPCR AGN 2.70E−02 — >100 — CHRM2 GPCR ANT — 3.20E−03 — >100 CNR1 GPCR AGN 1.00E−05 — >100 — CNR1 GPCR ANT — 6.20E−04 — >100 DRD1 GPCR AGN 9.10E−02 — >100 — DRD1 GPCR ANT — 7.10E−04 — 12.03 DRD2S GPCR AGN 5.10E−04 — >100 — DRD2S GPCR ANT — 9.60E−04 — 1.78 HTR1A GPCR AGN 1.70E−03 — 7.08 — HTR1A GPCR ANT — 4.60E−02 — >100 HTR1B GPCR AGN 9.00E−05 — 2.90E−01 — HTR1B GPCR ANT — 5.80E−03 — >100 HTR2B GPCR AGN 6.30E−04 — >100 — HTR2B GPCR ANT — 4.00E−04 — 1.20E−02 OPRD1 GPCR AGN 5.00E−05 — 51.46 — OPRD1 GPCR ANT — 5.80E−04 — >100 GABAA Ion channel OP 6.2 — >100 — GABAA Ion channel BL — 4.6 — >100 HTR3A Ion channel OP 3.00E−01 — >100 — HTR3A Ion channel BL — 1.90E−03 — 33.89 MAO-A Enzyme IN — 2.90E−03 — 76.01 DAT transporter BL — 1.40E−03 — >100 NET transporter BL — 6.70E−03 — >100 SERT transporter BL — 1.80E−03 — >100 NMDAR Ion channel BL — 8.00E−02 — >100 NMDAR Ion channel OP 4.40E−01 — >100 —

Example 2—Synthesis and Analysis of a Second C₄-Carboxylic Acid-Substituted Tryptamine Derivative

The synthesis of psilocin (1) has been described previously (Shirota et al., J. Nat. Prod. 2003, 66:885-887; Kargbo et al., ACS Omega 2020, 5:16959-16966). Referring to FIG. 4A, to a suspension of compound (1) (30 mg) in dry dichloromethane (DCM) (8 ml) was added 22 μl of triethylamine dropwise, and pentafluorobenzoyl chloride (34.6 l). After stirring for 5 minutes at room temperature, the mixture turned to clear solution. The mixture was stirred at room temperature for 1-2 hours and the reaction was monitored by thin layer chromatography (TLC). The reaction was then quenched by diluted aqueous HCl (0.5N) and extracted by DCM three times. The combined organic extracts were washed with water, brine and dried over anhydrous MgSO₄. After concentration by rotary evaporator, the mixture residue was applied to a silica column for chromatographic purification and eluted using 5% methanol in DCM to afford compound (3) as an off-white solid (21.2 mg, 36% yield). 1H NMR (CDCl₃) δ 7.38 (2H, m, ArH), 7.21 (1H, t, ArH), 6.94 (1H, dd, ArH), 3.45 (2H, dd, CH₂), 3.37 (2H, m, CH₂), 2.87 (6H, s, 2×NCH₃). LCMS result: cal mass for C₁₉H₁₆F₅N₂O₂ [M+H]: 399.1126, found: 399.1120. Purity was determined to be 95%. It is noted that compound (3) corresponds with the chemical compound having chemical formula C(VI):

Assessment of Cell Viability Upon Treatment of a Psilocin Derivative.

Cell viability was assessed as described for Example 1, except the compound with formula C(VI) was evaluated in place of the compound with formula C(V). Data acquired for the derivative having chemical formula (C-V) is displayed as “C-V” on the x-axes in FIG. 4B and FIG. 4C.

Radioligand Receptor Binding Assays.

Activity at 5-HT_(2A) receptor was assessed as described for Example 1, except the compound with formula C(VI) was evaluated in place of the compound with formula C(V). FIG. 4D shows radioligand competition assay results for compound with formula C(VI), depicted on the x-axis simply as “C-VI”.

Cell Lines and Control Ligands Used to Assess Activity at 5-HT_(IA).

Cell lines, cell line maintenance, and experimental procedures assessing modulation of 5-HT_(1A) were performed as described in Example 1, except that compound C(VI) was evaluated in place of compound C(V). 5-HT_(1A) receptor binding evaluation for compound with formula C(VI) (designated simply “C-VI” along the x-axis) is shown in FIG. 4E. Comparison of data acquired in +5-HT_(1A) cultures with those acquired in −5-HT_(1A) cultures suggests no receptor modulation at higher ligand concentrations.

Evaluation of Metabolic Stability in Human Intestine, Liver, and Serum Fractions In Vitro.

Evaluations of metabolic stability and capacity of novel molecules to release psilocin under various in vitro conditions were performed as described in Example 1, except that compound C(VI) was used in place of compound C(V) for all experiments. FIGS. 4F (i)-4F (iii) show the metabolic stability curves for compound with formula C(VI), designated “C-VI,” in control buffer (Panel A), AB serum (Panel B), HIM (Panel C), HLM (Panel D), HIS9 (Panel E), HLS9 (Panel F), alkaline phosphatase (Panel G), and esterase (Panel H).

In Vivo Evaluation of 5-HT_(2A) Receptor Agonism in Mice.

Evaluation of in vivo HTR was conducted as described in Example 1, except that compound C(VI) was used in place of compound C(V). Elevated incidences of HTR within the defined period of monitoring was observed in (1) psilocybin-treated mice, and (2) those treated with compound “C-VI,” relative to control mice treated with i.p. injected vehicle (0.9% NaCl). These results are illustrated in FIG. 4G, wherein compound with formula C(VI) is designated “C-VI.”

Mouse Pharmacokinetic (PK) Evaluation of Drug Metabolism to Psilocin.

Pharmacokinetic (PK) evaluations were performed in the same manner as described in Example 1, except compound C(VI) was used in place of compound C(V). Notably, compound C(VI) was not detectable in any animals at any dose, suggesting a degree of instability and/or quick conversion to psilocin. Thus, only psilocin PK analysis was performed.

Results for psilocin PK following C(VI) administration are found in Tables 15A-15B (1 mg/kg IV dose), Tables 16A-16B (1 mg/kg oral dose), Tables 17A-17B (3 mg/kg oral dose), Tables 18A-18B (10 mg/kg oral dose), Table 19 (comparative summary for IV data), Table 20 (comparative summary for oral data), Table 21A (psilocin exposure) and FIGS. 4H (i) and 4H (ii).

TABLE 15A Plasma concentrations of psilocin following 1 mg/kg i.v. administration of C(VI). Experimental Plasma concentration (ng/mL) time (h) M01 M02 M03 Mean ± SD 0.0833 26.7 35.4 35.2 32.4 ± 4.97 0.25 24.6 36.2 28.6 29.8 ± 5.89 0.5 11.6 12.6 8.66 11.0 ± 2.05 1 4.58 4.62 3.52  4.24 ± 0.624 2 1.34 1.91 1.13  1.46 ± 0.404 4 0.506 0.446 0.513  0.488 ± 0.0368 6 0.172 0.216 0.236  0.208 ± 0.0327 8 BLQ BLQ BLQ n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). n/a denotes not applicable.

TABLE 15B Summary of plasma PK parameters for psilocin following 1 mg/kg i.v. administration of C(VI)^(a). Parameter estimate for each animal Parameter M01 M02 M03 Mean ± SD t_(max) (h) 0.0833 0.250 0.0833  0.139 ± 0.0962 C_(max) (ng/mL) 26.7 36.2 35.2 32.7 ± 5.22 C_(max)/Dose^(a) 26.7 36.2 35.2 32.7 ± 5.22 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.35 1.27 1.77  1.46 ± 0.268 AUC_(0-tlast) 18.5 22.7 18.2 19.8 ± 2.55 (h*ng/mL) AUC_(0-tlast)/Dose^(a) 18.5 22.7 18.2 19.8 ± 2.55 (h*kg*ng/mL/mg) AUC_(0-inf) 18.8 23.1 18.8 20.2 ± 2.51 (h*ng/mL) MRT_(0-inf) (h) 1.02 0.954 1.10   1.02 ± 0.0705 ^(a)C(VI) dose was used.

TABLE 16A Plasma concentrations of psilocin following 1 mg/kg oral administration of C(VI). Experimental Plasma concentration (ng/mL) time (h) M04 M05 M06 Mean ± SD  0.25 334 8.80 10.6  9.70 (n = 2)  0.5 7.79 9.62 8.81  8.74 ± 0.917  1 4.38 5.09 5.15  4.87 ± 0.428  2 2.11 0.922 2.08  1.70 ± 0.677  4 0.666 0.296 0.212 0.391 ± 0.242  6 0.372 0.158 0.197 0.242 ± 0.114  8 0.274 BLQ BLQ 0.274 (n = 1) 24 BLQ No Peak No Peak n/a Bolded value is considered an outlier and was excluded from calculations. BLQ denotes below the lower limit of quantitation (0.2 ng/mL). Value in italics is below the lower limit of quantitation (BLQ, 0.2 ng/mL) but was included in calculations. n/a denotes not applicable.

TABLE 16B Summary of plasma PK parameters for psilocin following 1 mg/kg oral administration of C(VI)^(a). Parameter estimate for each animal Parameter M04 M05 M06 Mean ± SD t_(max) (h) 0.500 0.500 0.250 0.417 ± 0.144 C_(max) (ng/mL) 7.79 9.62 10.6 9.34 ± 1.43 C_(max)/Dose^(a) 7.79 9.62 10.6 9.34 ± 1.43 (kg*ng/mL/mg) Apparent t_(1/2) (h) 3.12 1.57 0.999 1.90 ± 1.10 AUC_(0-tlast) (h*ng/mL) 12.2 10.9 12.6  11.9 ± 0.854 AUC_(0-tlast)/Dose^(a) 12.2 10.9 12.6  11.9 ± 0.854 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 13.4 11.3 12.9 12.5 ± 1.09 MRT_(0-inf) (h) 2.94 1.35 1.32  1.87 ± 0.928 ^(a)C(VI) dose was used.

TABLE 17A Plasma concentrations of psilocin following 3 mg/kg oral administration of C(VI). Experimental Plasma concentration (ng/mL) time (h) M07 M08 M09 Mean ± SD  0.25 21.5 31.3 35.2 29.3 ± 7.06  0.5 27.8 28.0 27.2  27.7 ± 0.416  1 20.1 11.9 22.0 18.0 ± 5.37  2 6.01 6.20 6.44  6.22 ± 0.215  4 0.865 0.912 0.843  0.873 ± 0.0352  6 0.640 0.556 0.455  0.550 ± 0.0926  8 0.133 0.129 0.118   0.127 ± 0.00777 24 BLQ BLQ No Peak n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). n/a denotes not applicable.

TABLE 17B Summary of plasma PK parameters for psilocin following 3 mg/kg oral administration of C(VI). Parameter estimate for each animal Parameter M07 M08 M09 Mean ± SD t_(max) (h) 0.500 0.250 0.250 0.333 ± 0.144 C_(max) (ng/mL) 27.8 31.3 35.2 31.4 ± 3.70 C_(max)/Dose^(a) 9.27 10.4 11.7 10.5 ± 1.23 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.48 1.42 1.41  1.44 ± 0.0388 AUC_(0-tlast) 39.8 37.0 44.3 40.4 ± 3.70 (h*ng/mL) AUC_(0-tlast)/Dose^(a) 13.3 12.3 14.8 13.5 ± 1.23 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 40.1 37.3 44.6 40.7 ± 3.68 MRT_(0-inf) (h) 1.42 1.39 1.29  1.37 ± 0.0690 ^(a)C(VI) dose was used.

TABLE 18A Plasma concentrations of psilocin following 10 mg/kg oral administration of C(VI). Experimental Plasma concentration (ng/mL) time (h) M10 M11 M12 Mean ± SD  0.25 66.6 55.1 95.9 72.5 ± 21.0  0.5 56.4 51.3 105 70.9 ± 29.6  1 30.5 39.3 46.8 38.9 ± 8.16  2 17.3 18.4 21.1 18.9 ± 1.96  4 4.96 3.98 2.34 3.76 ± 1.32  6 1.27 1.03 2.39  1.56 ± 0.726  8 0.709 0.461 0.477 0.549 ± 0.139 24 BLQ BLQ BLQ n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). n/a denotes not applicable.

TABLE 18B Summary of plasma PK parameters for psilocin following 10 mg/kg oral administration of C(VI)^(a). Parameter estimate for each animal Parameter M10 M11 M12 Mean ± SD t_(max) (h) 0.250 0.250 0.500 0.333 ± 0.144 C_(max) (ng/mL) 66.6 55.1 105 75.6 ± 26.1 C_(max)/Dose^(a) 6.66 5.51 10.5 7.56 ± 2.61 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.27 1.12 1.22  1.20 ± 0.0768 AUC_(0-tlast) 95.1 94.9 130  107 ± 20.0 (h*ng/mL) AUC_(0-tlast)/Dose^(a) 9.51 9.49 13.0 10.7 ± 2.00 (h*kg*ng/mL/mg) AUC_(0-inf) 96.4 95.6 130  107 ± 19.9 (h*ng/mL) MRT_(0-inf) (h) 1.70 1.60 1.36  1.55 ± 0.172 ^(a)C(VI) dose was used.

TABLE 19 Comparative summary of psilocin pharmacokinetic (PK) parameters following intravenous (IV) dosing of psilocybin or compound C(VI)^(a). Parameter Psilocybin C(VI) Nominal prodrug dose 1 1 (mg/kg) t_(max) (h)  0.139 ± 0.0962  0.139 ± 0.0962 C_(max) (ng/mL)  105 ± 19.8 32.7 ± 5.22 C_(max)/Dose^(a)  105 ± 19.8 32.7 ± 5.22 (kg*ng/mL/mg) Apparent t_(1/2) (h) 0.905 (n = 1)  1.46 ± 0.268 AUC_(0-tlast) (h*ng/mL) 89.8 ± 17.5 19.8 ± 2.55 AUC_(0-tlast)/Dose^(a) 89.8 ± 17.5 19.8 ± 2.55 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL)   110 (n = 1) 20.2 ± 2.51 MRT_(0-inf) (h)  1.64 (n = 1)   1.02 ± 0.0705 ^(a)Prodrug dose was used.

TABLE 20 Comparative summary of psilocin pharmacokinetic (PK) parameters following oral (PO) dosing of psilocybin or compound C(VI). Parameter Psilocybin C(VI) Nominal prodrug 1 3 10 1 3 10 dose (mg/kg) t_(max) (h) 0.333 ± 0.144 0.417 ± 0.144 0.333 ± 0.144 0.417 ± 0.144 0.333 + 0.144 0.333 ± 0.144 C_(max) (ng/mL) 53.7 ± 3.50 52.9 ± 10.5  243 ± 43.7 9.34 ± 1.43 31.4 ± 3.70 75.6 ± 26.1 C_(max)/Dose^(a) 1.56 17.6 ± 3.48 24.3 ± 4.37 9.34 ± 1.43 10.5 ± 1.23 7.56 ± 2.61 (kg*ng/mL/mg) Apparent t_(1/2) (h) 2.15 (n = 1) 4.51 (n = 2)  3.58 ± 0.920 1.90 ± 1.10  1.44 ± 0.0388  1.20 ± 0.0768 AUC_(0-tlast) 67.1 ± 1.61 84.4 ± 10.8  397 ± 55.5  11.9 ± 0.854 40.4 ± 3.70  107 ± 20.0 (h*ng/mL) AUC_(0-tlast)/Dose^(a) 34.4 ± 2.24 28.1 ± 3.61 39.7 ± 5.55  11.9 ± 0.854 13.5 ± 1.23 10.7 ± 2.00 (h*kg*ng/mL/mg) AUC_(0-inf) 70.4 (n = 1) 80.5 (n = 2)  398 ± 55.1 12.5 ± 1.09 40.7 ± 3.68  107 ± 19.9 (h*ng/mL) MRT_(0-inf) (h) 1.53 (n = 1) 2.04 (n = 2)  2.39 ± 0.236  1.87 ± 0.928  1.37 ± 0.0690  1.55 ± 0.172

TABLE 21A Summary of mean plasma exposure of psilocin as a function of C(VI) dose. C(VI) dose Parameter 1 mg/kg i.v. 1 mg/kg p.o. 3 mg/kg p.o. 10 mg/kg p.o. C_(max)/Dose^(a) (kg*ng/mL/mg) 32.7 ± 5.22 9.34 ± 1.43 10.5 ± 1.23 7.56 ± 2.61 Apparent t_(1/2) (h)  1.46 ± 0.268 1.90 ± 1.10  1.44 ± 0.0388  1.20 ± 0.0768 AUC_(0-tlast)/Dose^(a) 19.8 ± 2.55  11.9 ± 0.854 13.5 ± 1.23 10.7 ± 2.00 (h*kg*ng/mL/mg)

In Vitro Survey of Pharmacological Interaction Profiles at Receptors, Transporters and Enzymes Linked to Targeted Health Conditions.

All assays were performed as described in Example 1, except compound C(VI) was used in place of C(V). To assess assay performance and establish positive control benchmarks, ligands listed in Table 14B were evaluated alongside test derivative. Results for all assays using compound C(VI) or positive controls are shown in Table 21B.

TABLE 21B Data summary table of target assays for compound C(VI) and control ligands. Potency (EC₅₀ or IC₅₀) is provided in units of μM. AGN, agonist; ANT, antagonist; OP, opener; BL, blocker; IN, inhibitor. Target name Target type Assay type EC₅₀ (control) IC₅₀ (control) EC₅₀ (C-VI) IC₅₀ (C-VI) ADRA1A GPCR AGN 5.00E−05 — 34.41 — ADRA1A GPCR ANT — 9.60E−04 — 26.88 ADRA2A GPCR AGN 4.00E−05 — 65.08 — ADRA2A GPCR ANT — 3.10E−03 — >100 AVPR1A GPCR AGN 4.20E−04 — >100 — AVPR1A GPCR ANT — 1.60E−03 — >100 CHRM1 GPCR AGN 9.70E−03 — >100 — CHRM1 GPCR ANT — 6.10E−03 — >100 CHRM2 GPCR AGN 2.70E−02 — >100 — CHRM2 GPCR ANT — 3.20E−03 — >100 CNR1 GPCR AGN 1.00E−05 — 62.92 — CNR1 GPCR ANT — 6.20E−04 — >100 DRD1 GPCR AGN 9.10E−02 — >100 — DRD1 GPCR ANT — 7.10E−04 — 51.63 DRD2S GPCR AGN 5.10E−04 — 1.09 — DRD2S GPCR ANT — 9.60E−04 — >100 HTR1A GPCR AGN 1.70E−03 — 2.21 — HTR1A GPCR ANT — 4.60E−02 — >100 HTR1B GPCR AGN 9.00E−05 — 1.00E−01 — HTR1B GPCR ANT — 5.80E−03 — >100 HTR2B GPCR AGN 6.30E−04 — >100 — HTR2B GPCR ANT — 4.00E−04 — 0.03 OPRD1 GPCR AGN 5.00E−05 — 59.41 — OPRD1 GPCR ANT — 5.80E−04 — >100 GABAA Ion channel OP 6.2 — >100 — GABAA Ion channel BL — 4.6 — >100 HTR3A Ion channel OP 3.00E−01 — >100 — HTR3A Ion channel BL — 1.90E−03 — 55.13 MAO-A Enzyme IN — 2.90E−03 — 20.68 DAT transporter BL — 1.40E−03 — >100 NET transporter BL — 6.70E−03 — >100 SERT transporter BL — 1.80E−03 — 34.29 NMDAR Ion channel BL — 8.00E−02 — >100 NMDAR Ion channel OP 4.40E−01 — >100 —

Example 3—Synthesis and Analysis of a Third C₄-Carboxylic Acid-Substituted Tryptamine Derivative

The synthesis of psilocin (1) has been described previously (Shirota et al., J. Nat. Prod. 2003, 66:885-887; Kargbo et al., ACS Omega 2020, 5:16959-16966). Referring to FIG. 5A, to a flame-dried flask was added compound (1) (50 mg, 0.25 mmol, 2.0 eq), and anhydrous dichloromethane (DCM) (1 mL) under argon. Triethylamine (34 μL, 0.25 mmol, 2.0 eq) was added, followed by isophthaloyl chloride (25 mg, 0.12 mmol, 1.0 eq) dissolved in anhydrous dichloromethane (1 mL). The mixture was refluxed overnight, then directly purified using flash chromatography on 4 g normal-phase silica and eluted with a 10-20% (methanol-dichloromethane) gradient to afford compound (4) (19.6 mg, 30% yield) as a tan oil. ¹H NMR (400 MHz, methanol-d4) δ 9.13 (td, J=1.8, 0.6 Hz, 1H), 8.70 (dd, J=7.8, 1.8 Hz, 2H), 7.95 (td, J=7.8, 0.6 Hz, 1H), 7.42-7.37 (m, 2H), 7.29 (t, J=0.9 Hz, 2H), 7.24-7.18 (m, 2H), 6.93 (dd, J=7.7, 0.8 Hz, 2H), 3.41-3.36 (m, 4H), 3.20-3.14 (m, 4H), 2.73 (s, 12H). Purity was determined to be 95%. It is noted that compound (4) corresponds with the chemical compound having chemical formula C(VII):

Assessment of Cell Viability Upon Treatment of a Psilocin Derivative.

Cell viability was assessed as described for Example 1, except the compound with formula C(VII) was evaluated in place of the compound with formula C(V). Data acquired for the derivative having chemical formula (C-VII) is displayed as “C-VII” on the x-axis in FIG. 5B.

Radioligand Receptor Binding Assays.

Activity at 5-HT_(2A) receptor was assessed as described for Example 1, except the compound with formula C(VII) was evaluated in place of the compound with formula C(V). FIG. 5C shows radioligand competition assay results for compound with formula C(VII), depicted on the x-axis simply as “C-VII”.

Cell Lines and Control Ligands Used to Assess Activity at 5-HT_(IA).

Cell lines, cell line maintenance, and experimental procedures assessing modulation of 5-HT_(1A) were performed as described in Example 1, except that compound C(VII) was evaluated in place of compound C(V). 5-HT_(1A) receptor binding evaluation for compound with formula C(VII) (designated simply “C-VII” along the x-axis) is shown in FIG. 5D. Comparison of data acquired in +5-HT_(1A) cultures with those acquired in −5-HT_(1A) cultures suggests no significant receptor modulation.

Evaluation of Metabolic Stability in Human Intestine, Liver, and Serum Fractions In Vitro.

Evaluations of metabolic stability and capacity of novel molecules to release psilocin under various in vitro conditions were performed as described in Example 1, except that compound C(VII) was used in place of compound C(V) for all experiments. FIGS. 5E (i) and 5E(ii) shows the metabolic stability curves for compound with formula C(VII), designated “C-VII” in assays containing HLM (Panel A), HLS9 (Panel B), HIM (Panel C), HIS9 (Panel D), AB serum (Panel E) and Esterase (Panel F).

In Vivo Evaluation of 5-HT_(2A) Receptor Agonism in Mice.

Evaluation of in vivo HTR was conducted as described in Example 1, except that compound C(VII) was used in place of compound C(V). Elevated incidences of HTR within the defined period of monitoring was observed in (1) psilocybin-treated mice, and (2) those treated with compound “C-VII,” relative to control mice treated with i.p. injected vehicle (0.9% NaCl). These results are illustrated in FIG. 5F, wherein compound with formula C(VII) is designated simply “C-VII.” Results for control mice injected with vehicle are not shown in FIG. 5F, but are the same as those in Examples 1 and 2 since HTR experiments were run with the same control cohorts.

Example 4—Synthesis and Analysis of a Fourth C₄-Carboxylic Acid-Substituted Tryptamine Derivative

The synthesis of psilocin (1) has been described previously (Shirota et al., J. Nat. Prod. 2003, 66:885-887; Kargbo et al., ACS Omega 2020, 5:16959-16966). Referring to FIG. 6A, Compound (1) (100 mg, 0.49 mmol, 1.0 eq) was suspended in anhydrous dichloromethane (DCM) (0.5 mL) under argon atmosphere. Triethylamine (0.10 mL, 0.73 mmol, 1.5 eq) was added, followed by m-PEG2-CH₂ acid chloride (96 mg, 0.49 mmol, 1.0 eq) diluted with anhydrous dichloromethane (0.2 mL). The resulting mixture was stirred at room temperature for 23 μhours and monitored by TLC (20% methanol/dichloromethane). Solvent was removed under reduced pressure, and the crude mixture was purified by flash column chromatography on 12 g normal-phase silica using 10% methanol/dichloromethane as eluent. The resulting crude product was further purified by flash column chromatography on 4 g normal-phase silica using an 8 to 10% methanol/dichloromethane gradient as eluent to yield (11) (3.9 mg, 2.2% yield) as a colourless oil. ¹H NMR (400 MHz, methanol-d4) δ 7.32 (dd, J=8.2, 0.8 Hz, 1H), 7.27 (s, 1H), 7.15 (t, J=8.0 Hz, 1H), 6.88 (dd, J=7.8, 0.8 Hz, 1H), 4.58 (s, 2H), 3.92-3.85 (m, 2H), 3.78-3.72 (m, 2H), 3.70-3.64 (m, 2H), 3.59-3.52 (m, 2H), 3.48-3.42 (m, 2H), 3.37 (s, 3H), 3.26-3.17 (m, 3H), 2.94 (s, 6H). Purity was determined to be 95%. It is noted that compound (11) corresponds with the chemical compound having chemical formula C(III):

Assessment of Cell Viability Upon Treatment of a Psilocin Derivative.

Cell viability was assessed as described for Example 1, except the compound with formula C(III) was evaluated in place of the compound with formula C(V). Data acquired for the derivative having chemical formula (C-III) is displayed as “C-III” on the x-axes of FIG. 6B and FIG. 6C.

Radioligand Receptor Binding Assays.

Activity at 5-HT_(2A) receptor was assessed as described for Example 1, except the compound with formula C(III) was evaluated in place of the compound with formula C(V). FIG. 6D shows radioligand competition assay results for compound with formula C(III), depicted on the x-axis simply as “C-III”.

Cell Lines and Control Ligands Used to Assess Activity at 5-HT_(IA).

Cell lines, cell line maintenance, and experimental procedures assessing modulation of 5-HT_(1A) were performed as described in Example 1, except that compound C(III) was evaluated in place of compound C(V). 5-HT_(1A) receptor binding evaluation for compound with formula C(III) (designated simply “C-III” along the x-axis) is shown in FIG. 6E. Comparison of data acquired in +5-HT_(1A) cultures with those acquired in −5-HT_(1A) cultures suggests significant receptor modulation.

Evaluation of Metabolic Stability in Human Intestine, Liver, and Serum Fractions In Vitro.

Evaluations of metabolic stability and capacity of novel molecules to release psilocin under various in vitro conditions were performed as described in Example 1, except that compound C(III) was used in place of compound C(V) for all experiments. FIGS. 6F (i)-6F (ii) show the metabolic stability curves for compound with formula C(III), designated “C-III” in assays containing HLM (Panel A), HLS9 (Panel B), HIM (Panel C), HIS9 (Panel D), AB serum (Panel E) and Buffer (Panel F).

In Vivo Evaluation of 5-HT_(2A) Receptor Agonism in Mice.

Evaluation of in vivo HTR was conducted as described in Example 1, except that compound C(III) was used in place of compound C(V). Elevated incidences of HTR within the defined period of monitoring was observed in (1) psilocybin-treated mice, and (2) those treated with compound “C-III,” relative to control mice treated with i.p. injected vehicle (0.9% NaCl). These results are illustrated in FIG. 6G, wherein compound with formula C(III) is designated simply “C-III.” Results for control mice injected with vehicle are not shown in FIG. 6F, but are the same as those in Examples 1 and 2 since HTR experiments were run with the same control cohorts.

Example 5—Synthesis and Analysis of a Fifth C₄-Carboxylic Acid-Substituted Tryptamine Derivative

The synthesis of psilocin (1) has been described previously (Shirota et al., J. Nat. Prod. 2003, 66:885-887; Kargbo et al., ACS Omega 2020, 5:16959-16966). Referring to FIG. 7A, to a suspension of compound 1 (102 mg, 0.50 mmol, 2.0 eq) in dry DCM (1.5 mL) under argon atmosphere was added triethylamine (70 μL, 0.50 mmol, 2.0 eq) followed by isophthaloyl dichloride (51 mg, 0.25 mmol, 1.0 eq) dissolved in dry DCM (0.5 mL). The reaction mixture was allowed to stir at room temperature for 18 hours. The crude reaction mixture was directly purified via flash chromatography on 4 g normal-phase silica and eluted with a 10 to 20% methanol-dichloromethane gradient to yield a mixture of products. This mixture was further purified by flash column chromatography on 4 g normal-phase silica and eluted with 10% methanol-dichloromethane to yield compound 13 (7 mg, 8%) as a colourless oil. The calculated MS-ESI value was 367.1652, compared with observed value 367.1650 m/z [M+H]⁺. ¹H NMR (400 MHz, MeOD) δ 8.91 (td, J=1.8, 0.6 Hz, 1H), 8.54 (ddd, J=7.8, 1.8, 1.2 Hz, 1H), 8.40 (dt, J=7.9, 1.4 Hz, 1H), 7.80 (td, J=7.8, 0.6 Hz, 1H), 7.38 (dd, J=8.2, 0.8 Hz, 1H), 7.27 (d, J=0.8 Hz, 1H), 7.21 (t, J=7.9 Hz, 1H), 6.91 (dd, J=7.7, 0.8 Hz, 1H), 4.00 (s, 3H), 3.29 (dd, J=8.6, 6.8 Hz, 2H), 3.12-3.06 (m, 2H), 2.65 (s, 6H). Purity was determined to be 95%. Continuing to refer to FIG. 7A, it is noted that compound 13 corresponds with the chemical compound having chemical formula C(XLIII):

Assessment of Cell Viability Upon Treatment of a Psilocin Derivative.

Cell viability was assessed as described for Example 1, except the compound with formula C(XLIII) was evaluated in place of the compound with formula C(V). Data acquired for the derivative having chemical formula (C-XLIII) is displayed as “C-XLIII” on the x-axes of FIG. 7B and FIG. 7C.

Radioligand Receptor Binding Assays.

Activity at 5-HT_(2A) receptor was assessed as described for Example 1, except the compound with formula C(XLIII) was evaluated in place of the compound with formula C(V). FIG. 7D shows radioligand competition assay results for compound with formula C(XLIII), depicted on the x-axis simply as “C-XLIII”.

Cell Lines and Control Ligands Used to Assess Activity at 5-HT_(IA).

Cell lines, cell line maintenance, and experimental procedures assessing modulation of 5-HT_(1A) were performed as described in Example 1, except that compound C(XLIII) was evaluated in place of compound C(V). 5-HT_(1A) receptor binding evaluation, including EC₅₀ for compound with formula C(XLIII) (designated simply “C-XLIII” along the x-axis) is shown in FIG. 7E. Comparison of data acquired in +5-HT_(1A) cultures with those acquired in −5-HT_(1A) cultures suggests receptor modulation at higher ligand concentrations.

Evaluation of Metabolic Stability in Human Intestine, Liver, and Serum Fractions In Vitro.

Evaluations of metabolic stability and capacity of novel molecules to release psilocin under various in vitro conditions were performed as described in Example 1, except that compound C(XLIII) was used in place of compound C(V) for all experiments. FIGS. 7F (i) and 7F(ii) shows the metabolic stability curves for compound with formula C(XLIII), designated “C-XLIII” in assays containing HLM (Panel A), HLS9 (Panel B), HIM (Panel C), HIS9 (Panel D), AB serum (Panel E) and Buffer (Panel F).

Example 6—Synthesis and Analysis of a Sixth C₄-Carboxylic Acid-Substituted Tryptamine Derivative

This Example 6 initially describes an example method for synthesis of an example C₄-carboxylic acid substituted tryptamine derivative, notably a compound having chemical formula C(I). Referring to FIG. 8A, a dry, 3-neck RBF was charged with 4-benzyloxyindole (1) (14.0 g, 62.7 mmol) and Et₂O (327 mL) under Ar. The mixture was cooled down to 0° C. in an ice bath. An Argon sparge was placed on the RBF and into the reaction mixture to purge out the HCl gas released from the reaction. Oxalyl chloride (10.9 mL, 129 mmol) was added dropwise over 40 min, while maintaining the cold temperature. The mixture was stirred for 4 h at 0° C. to yield (2). The argon sparge was removed, and dimethylamine (157 mL, 314 mmol) (2 M in THF) was added dropwise at 0° C. over 1 h using an addition funnel. The mixture was allowed to warm up to RT and stir overnight. Diethyl ether (200 mL) was added, and the mixture was cooled down to 0° C. The resulting precipitate (crude (3) was filtered and transferred to an Erlenmeyer flask. The solid was suspended in water (300 mL) and stirred for 30 min. Then, it was filtered and washed with more H₂O to remove residual salts. The crude solid was further dried in vacuo and used in the next step without further purification.

Continuing to refer to FIG. 8A, lithium aluminum hydride (60.2 mL, 120 mmol) (2M in THF) was added to a dry 3-neck flask under Argon. The flask was fitted with a reflux condenser and an addition funnel. Dry 1,4-dioxane (100 mL) was added, and the mixture was heated to 60° C. in an oil bath. In a separate flask, compound (3) (7.46 g, 23.1 mmol) was dissolved in a mixture of THF (60 mL) and 1,4-dioxane (120 mL). With rapid stirring, this solution was added dropwise to the reaction flask over 1 h using an addition funnel. The oil bath temperature was held at 70° C. for 4 h, followed by vigorous reflux overnight (16 h) in an oil bath temperature of 95° C.

Continuing to refer to FIG. 8A, the reaction was placed in an ice bath, and a solution of distilled H₂O (25 mL) in THF (65 mL) was added dropwise to quench LiAlH₄, resulting in a gray flocculent precipitate. Et₂O (160 mL) was added to assist breakup of the complex and improve filtration. This slurry was stirred for 1 h and the mixture was then filtered using a Buchner funnel. The filter cake was washed on the filter with warm Et₂O (2×200 mL) and was broken up, transferred back into the reaction flask and vigorously stirred with additional warm Et₂O (300 mL). This slurry was filtered, and the cake was washed on the filter with Et₂O (120 mL) and hexane (2×120 mL). All the organic filtrates were combined and dried (MgSO₄). After the drying agent was removed by filtration, the filtrate was concentrated under vacuum and dried under high vacuum. The crude residue was triturated with EtOAc/hex (1:9, 25 mL) to afford the crude product (4) which was used in the next step without further purification.

Continuing to refer to FIG. 8A, to a solution of (4) (5.00 g, 17.0 mmol) in dry THF (100 mL) cooled to −78° C. under argon was added dropwise a 1 M solution of KHMDS (18.7 mL, 18.7 mmol) in THF. After stirring at −78° C. for 1 h, a solution of TIPSCl (3.82 mL, 17.8 mmol) in THF (19.0 mL) was added dropwise over 15 minutes, and the reaction mixture was allowed to warm up to RT. After stirring at RT for 1 h, the reaction was quenched with H₂O (40 mL), THF was evaporated under reduced pressure, and the aqueous solution was further diluted with H₂O (75 mL) and extracted with DCM (3×100 mL). The organic layers were combined and washed with brine, dried over Na₂SO₄, filtered, and concentrated under reduced pressure. The crude product was purified by flash column chromatography (MeOH/DCM 5:95 to 10:90) to afford the pure product as a light brown oil (6.99 g, 91%). Product (5) was confirmed as follows: ¹H NMR (400 MHz, CDCl₃) δ 7.58-7.51 (m, 2H), 7.44-7.39 (m, 2H), 7.38-7.33 (m, 1H), 7.12 (dd, J=8.4, 0.8 Hz, 1H), 7.08-6.99 (m, 1H), 6.94 (s, 1H), 6.60 (dd, J=7.7, 0.7 Hz, 1H), 5.20 (s, 2H), 3.12-3.04 (m, 2H), 2.67-2.58 (m, 2H), 2.16 (s, 6H), 1.69 (h, J=7.5 Hz, 3H), 1.16 (d, J=7.5 Hz, 18H).

Continuing to refer to FIG. 8A, to a stirring solution of 5 (6.99 g, 15.5 mmol) dissolved in EtOH, 95% (310 mL), was added 10% palladium on carbon (1.65 g, 1.55 mmol). This mixture was put under vacuum for five minutes, then alternately purged with H₂ gas until pressurized hydrogen atmosphere was established, then allowed to stir for 75 minutes at room temperature. The palladium on carbon was removed by filtration through celite, the filtrate dried with anhydrous magnesium sulphate, and concentrated under reduced pressure to yield (6) (4.67 g, 84%) as an off-white solid. Data confirming G(I) are as follows: MS-ESI: calculated: 361.2670; observed: 361. 2668 m/z [M+H]⁺. ¹H NMR (400 MHz, MeOD) δ 6.98 (d, J=8.6 Hz, 2H), 6.91 (dd, J=8.4, 7.5 Hz, 1H), 6.42 (dd, J=7.5, 0.8 Hz, 1H), 3.06 (t, J=6.9 Hz, 2H), 2.77 (t, J=6.9 Hz, 2H), 2.39 (s, 6H), 1.72 (p, J=7.5 Hz, 3H), 1.16 (d, J=7.5 Hz, 18H).

Continuing to refer to FIG. 8A, to a solution of N,N-diisopropylethylamine (DIPEA) (114 μL, 653 μmol) and (6) (150 mg, 416 μmol) in DCM (2.50 mL) was added, in a dropwise manner, a solution of 4-bromobenzoyl chloride (93.2 mg, 416 μmol) in DCM (1.25 mL). The mixture was left to react at RT. After 3 hours the mixture contained very little starting material and the reaction mixture was poured into a separatory funnel containing 10 mL of water and 10 mL DCM. The aqueous phase was extracted with DCM (3×10 mL), all organic phases were combined, washed with brine, and dried over magnesium sulfate. Purification was carried out by column chromatography (9:1 DCM:MeOH) to leave (7) (193 mg, 85%) as a colorless oil. Product MM-594 was confirmed as follows: MS-ESI: calculated: 543.2037; observed: 543.2036 m/z [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 8.15 (d, J=8.6 Hz, 2H), 7.68 (d, J=8.6 Hz, 2H), 7.38 (dd, J=8.3, 0.8 Hz, 1H), 7.17-7.10 (m, 1H), 7.02 (s, 1H), 6.90 (dd, J=7.7, 0.7 Hz, 1H), 2.96-2.85 (m, 2H), 2.59 (t, J=8.1 Hz, 2H), 2.12 (s, 6H), 1.68 (m, J=7.5 Hz, 3H), 1.14 (d, J=7.5 Hz, 18H).

Continuing to refer to FIG. 8A, To a solution of (7) (175 mg, 322 μmol) in THE (2.0 mL) was added 1.0 M tetrabutylammonium fluoride solution (483 μL, 483 μmol) dropwise. After 30 min, the mixture was poured into a separatory funnel containing water (15 mL) and DCM (15 mL), the aqueous phase was extracted with DCM (3×15 mL), the combined organic layers were washed with brine, dried over anhydrous MgSO₄, filtered and concentrated. The crude material was purified by column chromatography (9:1 DCM:MeOH) to provide a white powder as (8) (80.0 mg, 64%). Product MM-597 was confirmed using the following data: MS-ESI: calculated: 387.0703; observed: 387.0704 m/z [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 7.87 (dd, J=8.2, 0.9 Hz, 1H), 7.66 (d, J=8.5 Hz, 2H), 7.58 (d, J=8.4 Hz, 2H), 7.23 (d, J=8.1 Hz, 1H), 6.89 (s, 1H), 6.81 (dd, J=8.0, 0.9 Hz, 1H), 2.93-2.86 (m, 2H), 2.79-2.73 (m, 2H), 2.42 (s, 6H). Purity was assessed at 95%. It is noted that compound (8) shown in FIG. 8A corresponds to a compound having chemical formula C(I):

Assessment of Cell Viability Upon Treatment of a Psilocin Derivative.

Cell viability was assessed as described for Example 1, except the compound with formula C(I) was evaluated in place of the compound with formula C(V). Data acquired for the derivative having chemical formula C(I) is displayed as “C-I” on the x-axes in FIG. 8B and FIG. 8C.

Radioligand Receptor Binding Assays.

Activity at 5-HT_(2A) receptor was assessed as described for Example 1, except the compound with formula C(I) was evaluated in place of the compound with formula C(V). FIG. 8D shows radioligand competition assay results for compound with formula C(I), depicted on the x-axis simply as “C-I”.

Cell Lines and Control Ligands Used to Assess Activity at 5-HT_(IA).

Cell lines, cell line maintenance, and experimental procedures assessing modulation of 5-HT_(1A) were performed as described in Example 1, except that compound C(I) was evaluated in place of compound C(V). 5-HT_(1A) receptor binding evaluation for compound with formula C(I) (designated simply “C-I” along the x-axis) is shown in FIG. 8E. Comparison of data acquired in +5-HT_(1A) cultures with those acquired in −5-HT_(1A) cultures suggests mild receptor modulation at higher ligand concentrations.

Evaluation of Metabolic Stability in Human Intestine, Liver, and Serum Fractions In Vitro.

Evaluations of metabolic stability and capacity of novel molecules to release psilocin under various in vitro conditions were performed as described in Example 1, except that compound C(I) was used in place of compound C(V) for all experiments. FIGS. 8F (i)-8F(ii) show the metabolic stability curves for compound with formula C(I), designated “C-I” in assays containing HLM (Panel A), HLS9 (Panel B), HIM (Panel C), HIS9 (Panel D), AB serum (Panel E) and Buffer (Panel F).

In Vivo Evaluation of 5-HT_(2A) Receptor Agonism in Mice.

Evaluation of in vivo HTR was conducted as described in Example 1, except that compound C(I) was used in place of compound C(V). Elevated incidences of HTR within the defined period of monitoring was observed in (1) psilocybin-treated mice, and (2) those treated with compound “C-I,” relative to control mice treated with i.p. injected vehicle (0.9% NaCl). These results are illustrated in FIG. 8G, wherein compound with formula C(I) is designated “C-I.”

Mouse Pharmacokinetic (PK) Evaluation of Drug Metabolism to Psilocin.

Pharmacokinetic (PK) evaluations were performed in the same manner as described in Example 1, except compound C(I) was used in place of compound C(V). Results for compound C(I) PK following C(I) administration are found in Tables 22A-22B (1 mg/kg IV dose), Tables 23A-23B (1 mg/kg oral dose), Tables 24A-24B (3 mg/kg oral dose), Tables 25A-25B (10 mg/kg oral dose), Table 26 (C(I) exposure), and FIG. 8H. Results for psilocin PK following C(I) administration are found in Tables 27A-27B (1 mg/kg IV dose), Tables 28A-28B (1 mg/kg oral dose), Tables 29A-29B (3 mg/kg oral dose), Tables 30A-30B (10 mg/kg oral dose), Table 31 (comparative summary for IV data), Table 32 (comparative summary for oral data), Table 33A (psilocin exposure) and FIGS. 8I (i) and 8(I) (ii).

TABLE 22A Plasma concentrations of C(I) following 1 mg/kg i.v. administration of C(I). Experimental Plasma concentration (ng/mL) time (h) M37 M38 M39 Mean ± SD 0.0833 2620 118 94.4  944 ± 1450 0.25 1250 58.5 48.2 452 ± 691 0.5 348 33.4 30.4 137 ± 183 1 128 17.9 13.8 53.2 ± 64.8 2 52.8 3.61 3.40 19.9 ± 28.5 4 8.88 0.984 0.509 3.46 ± 4.70 6 4.65 0.363 BLQ 2.51 (n = 2) 8 BLQ No Peak BLQ n/a Value in italics is below the lower limit of quantitation (BLQ, 0.5 ng/mL) but was included in calculations. BLQ denotes below the lower limit of quantitation (0.5 ng/mL). n/a denotes not applicable.

TABLE 22B Summary of plasma PK parameters for C(I) following 1 mg/kg i.v. administration of C(I). Parameter estimate for each animal Parameter M37 M38 M39 Mean ± SD C₀ (ng/mL) 3792 168 132 1360 ± 2100 Apparent t_(1/2)(h) 1.14 1.21 0.643 0.997 ± 0.309 AUC_(0-tlast) (h*ng/mL) 1006 63.7 51.4 374 ± 548 AUC_(0-tlast)/Dose^(a) 1006 63.7 51.4 374 ± 548 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 1014 64.4 51.9 377 ± 552 AUC_(0-inf)/Dose^(a) 1014 64.4 51.9 377 ± 552 (h*kg*ng/mL/mg) CL (mL/h/kg) 986 15534 19265 11900 ± 9660  MRT_(0-inf) (h) 0.568 0.780 0.657 0.668 ± 0.106 V_(SS) (mL/kg) 560 12109 12650 8440 ± 6830 M37 may be considered an outlier.

TABLE 23A Summary of plasma PK parameters for C(I) following 1 mg/kg oral administration of C(I). Experimental Plasma concentration (ng/mL) time (h) M40 M41 M42 Mean ± SD  0.25 0.617 0.410 0.910 0.646 ± 0.251  0.5 0.816 0.535 1.28 0.877 ± 0.376  1 0.775 BLQ 1.02 0.898 (n = 2)  2 0.474 BLQ 0.600 0.537 (n = 2)  4 0.352 BLQ BLQ 0.352 (n = 1)  6 BLQ BLQ BLQ n/a  8 BLQ BLQ BLQ n/a 24 No Peak No No n/a Peak Peak Value in italics is below the lower limit of quantitation (BLQ, 0.5 ng/mL) but was included in calculations. BLQ denotes below the lower limit of quantitation (0.5 ng/mL). n/a denotes not applicable.

TABLE 23B Summary of plasma PK parameters for C(I) following 1 mg/kg oral administration of C(I). Parameter estimate for each animal Parameter M40 M41 M42 Mean ± SD t_(max) (h) 0.500 0.500 0.500 0.500 ± 0.00  C_(max) (ng/mL) 0.816 0.54 1.28 0.877 ± 0.376 C_(max)/Dose 0.816 0.54 1.28 0.877 ± 0.376 (kg*ng/mL/mg) Apparent t_(1/2) (h) nc^(a) nc nc n/a^(b) AUC_(0-tlast) (h*ng/mL) 2.09 0.169 1.75 1.34 ± 1.02 AUC_(0-tlast)/Dose 2.09 0.169 1.75 1.34 ± 1.02 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) nc nc nc n/a MRT_(0-inf) (h) nc nc nc n/a F(%)^(c) 0.554 0.0450 0.465 0.355 ± 0.272 F(%)^(c, d) 3.59 0.291 3.01 2.30 ± 1.76 ^(a)nc denotes not calculable as the terminal phase is not well defined. ^(b)n/a denotes not applicable ^(c)AUC_(0-tlast) was used for p.o. group, thus value might be under-estimated. ^(d)If M37 is considered as an outlier.

TABLE 24A Plasma concentrations of C(I) following 3 mg/kg oral administration of C(I). Experimental Plasma concentration (ng/mL) time (h) M43 M44 M45 Mean ± SD  0.25 1.62 2.13 2.34  2.03 ± 0.370  0.5 1.95 2.16 1.99  2.03 ± 0.112  1 1.74 1.56 1.33  1.54 ± 0.206  2 0.932 0.705 0.720 0.786 ± 0.127  4 0.569 0.873 1.28 0.907 ± 0.357  6 0.371 0.310 0.250  0.310 ± 0.0605  8 BLQ BLQ BLQ n/a 24 No Peak No Peak No Peak n/a Values in italics are below the lower limit of quantitation (BLQ, 0.5 ng/mL) but were included in calculations BLQ denotes below the lower limit of quantitation (0.5 ng/mL). n/a denotes not applicable.

TABLE 24B Summary of plasma PK parameters for C(I) following 3 mg/kg oral administration of C(I). Parameter estimate for each animal Parameter M43 M44 M45 Mean ± SD t_(max) (h) 0.500 0.500 0.250 0.417 ± 0.144 C_(max) (ng/mL) 1.95 2.16 2.34  2.15 ± 0.195 C_(max)/Dose 0.650 0.720 0.780  0.717 ± 0.0651 (kg*ng/mL/mg) Apparent t_(1/2) (h)^(a) 3.01 nc^(b) nc 3.01 (n = 1) AUC_(0-tlast) (h*ng/mL) 5.26 5.47 5.91  5.54 ± 0.330 AUC_(0-tlast)/Dose 1.75 1.82 1.97  1.85 ± 0.110 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 6.87 nc  nc 6.87 (n = 1) MRT_(0-inf) (h) 4.12 nc  nc 4.12 (n = 1) F(%)^(c) 0.466 0.484 0.523  0.491 ± 0.0292 F(%)^(c,d) 3.02 3.13 3.39  3.18 ± 0.189 ^(a)For M43, apparent t_(1/2) estimate may not be accurate; sampling interval during the terminal phase <2 × t_(1/2). ^(b)nc denotes not calculable as the terminal phase is not well defined. ^(c)AUC_(0-tlast) was used for p.o. group, thus value might be under-estimated. ^(d)If M37 is considered as an outlier.

TABLE 25A Plasma concentrations of C(I) following 10 mg/kg oral administration of C(I). Experimental Plasma concentration (ng/mL) time (h) M46 M47 M48 Mean ± SD  0.25 7.20 3.73 6.07 5.67 ± 1.77  0.5 6.41 7.10 10.9 8.14 ± 2.42  1 3.79 5.29 7.46 5.51 ± 1.85  2 2.51 1.47 3.80 2.59 ± 1.17  4 1.71 2.06 3.01  2.26 ± 0.673  6 0.830 1.18 0.661 0.890 ± 0.265  8 0.253 1.10 0.283 0.545 ± 0.481 24 No Peak No Peak No Peak n/a Values in italics are below the lower limit of quantitation (BLQ, 0.5 ng/mL) but were included in calculations. BLQ denotes below the lower limit of quantitation (0.5 ng/mL). n/a denotes not applicable.

TABLE 25B Summary of plasma PK parameters for C(I) following 10 mg/kg oral administration of C(I). Parameter estimate for each animal Parameter M46 M47 M48 Mean ± SD t_(max) (h) 0.250 0.500 0.500 0.417 ± 0.144 C_(max) (ng/mL) 7.20 7.10 10.9 8.40 ± 2.17 C_(max)/Dose 0.720 0.710 1.09 0.840 ± 0.217 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.45 nc^(a) 1.17 1.31 (n = 2) AUC_(0-tlast) (h*ng/mL) 15.8 16.8 23.6 18.7 ± 4.25 AUC_(0-tlast)/Dose 1.58 1.68 2.36  1.87 ± 0.425 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 16.3 n/a^(b) 24.1 20.2 (n = 2) MRT_(0-inf) (h) 2.66 n/a 2.40 2.53 (n = 2) F(%)^(c) 0.419 0.447 0.627 0.498 ± 0.113 F(%)^(c,d) 2.71 2.90 4.06  3.22 ± 0.731 ^(a)nc denotes not calculable as the terminal phase is not well defined. ^(d)If M37 is considered as an outlier.

TABLE 26 Summary of mean plasma exposure of C(I) as a function of C(I) dose. C(I) dose Parameter 1 mg/kg i.v. 1 mg/kg p.o. 3 mg/kg p.o. 10 mg/kg p.o. C_(max)/Dose n/a^(a) 0.877 ± 0.376  0.717 ± 0.0651 0.840 ± 0.217 (kg*ng/mL/mg) Apparent t_(1/2) (h) 0.997 ± 0.309 nc^(b) 3.01 (n = 1) 1.31 (n = 2) AUC_(0-tlast)/Dose 57.6 (n = 2) 1.34 ± 1.02  1.85 ± 0.110  1.87 ± 0.425 (h*kg*ng/mL/mg) F(%) n/a  0.355 ± 0.272  0.491 ± 0.0292 0.498 ± 0.113 F(%)^(c) n/a  2.30 ± 1.76  3.18 ± 0.189  3.22 ± 0.731 ^(a)n/a denotes not applicable. ^(b)nc denotes not calculable as the terminal phase is not well defined. ^(c)M37 is considered as an outlier.

TABLE 27A Plasma concentrations of psilocin following 1 mg/kg i.v. administration of C(I). Experimental Plasma concentration (ng/mL) time (h) M37 M38 M39 Mean ± SD 0.0833 51.1 4.60 4.28 20.0 ± 26.9 0.25 43.4 5.18 6.01 18.2 ± 21.8 0.5 24.7 7.88 7.96 13.5 ± 9.69 1 13.5 5.17 4.82 7.83 ± 4.91 2 7.32 1.38 1.81 3.50 ± 3.31 4 1.55 0.393 0.386 0.776 ± 0.670 6 0.645 0.183 BLQ 0.414 (n = 2) 8 0.240 BLQ BLQ 0.240 (n = 1) Value in italics is below the lower limit of quantitation (BLQ, 0.2 ng/mL) but was included in calculations. BLQ denotes below the lower limit of quantitation (0.2 ng/mL). n/a denotes not applicable.

TABLE 27B Summary of plasma PK parameters for psilocin following 1 mg/kg i.v. administration of C(I)^(a). Parameter estimate for each animal Parameter M37 M38 M39 Mean ± SD t_(max) (h) 0.0833 0.500 0.500 0.0833 ± 0.00   C_(max) (ng/mL) 51.1 7.88 7.96 22.3 ± 24.9 C_(max)/Dose^(a) 51.1 7.88 7.96 22.3 ± 24.9 (kg*ng/mL/mg) Apparent t_(1/2) (h)^(b) 1.49 1.37 0.833  1.23 ± 0.349 AUC_(0-tlast) (h*ng/mL) 48.0 10.8 10.8 23.2 ± 21.4 AUC_(0-tlast)/Dose^(a) 48.0 10.8 10.8 23.2 ± 21.4 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 48.5 11.2 11.3 23.7 ± 21.5 MRT_(0-inf) (h) 1.38 1.53 1.33  1.41 ± 0.103 ^(a)C(I) dose. M37 may be an outlier.

TABLE 28A Plasma concentrations of psilocin following 1 mg/kg oral administration of C(I). Experimental Plasma concentration (ng/mL) time (h) M40 M41 M42 Mean ± SD  0.25 2.13 1.84 1.96  1.98 ± 0.146  0.5 2.77 2.73 2.55  2.68 ± 0.117  1 1.97 1.51 1.76  1.75 ± 0.230  2 1.65 1.16 0.73  1.18 ± 0.458  4 0.796 0.621 0.597 0.671 ± 0.109  6 0.252 0.421 0.250  0.308 ± 0.0982  8 0.190 0.111 BLQ 0.151 (n = 2) 24 No Peak BLQ No Peak n/a Value in italics is below the lower limit of quantitation (BLQ, 0.2 ng/mL) but was included in calculations. BLQ denotes below the lower limit of quantitation (0.2 ng/mL). n/a denotes not applicable.

TABLE 28B Summary of plasma PK parameters for psilocin following 1 mg/kg oral administration of C(I). Parameter estimate for each animal Parameter M40 M41 M42 Mean ± SD t_(max) (h) 0.5000 0.500 0.500 0.500 ± 0.00  C_(max) (ng/mL) 2.77 2.73 2.55  2.68 ± 0.117 C_(max)/Dose^(a) 2.77 2.73 2.55  2.68 ± 0.117 (kg*ng/mL/mg) Apparent t_(1/2) (h)^(b) 1.82 1.87 2.59  2.09 ± 0.432 AUC_(0-tlast) (h*ng/mL) 7.59 6.38 5.16 6.38 ± 1.21 AUC_(0-tlast)/Dose^(a) 7.59 6.38 5.16 6.38 ± 1.21 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 8.08 6.68 6.10 6.95 ± 1.02 MRT_(0-inf) (h) 2.91 2.91 3.22  3.01 ± 0.179 ^(a)C(I) dose. ^(b)For M42, apparent t_(1/2) estimate may not be accurate; sampling interval during the terminal phase <2 × t_(1/2).

TABLE 29A Plasma concentrations of psilocin following 3 mg/kg oral administration of C(I). Experimental Plasma concentration (ng/mL) time (h) M43 M44 M45 Mean ± SD  0.25 7.52 12.4 17.1 12.3 ± 4.79  0.5 7.35 12.7 12.7 10.9 ± 3.09  1 8.13 7.66 7.40  7.73 ± 0.370  2 3.11 1.82 2.60  2.51 ± 0.650  4 0.940 0.626 1.49  1.02 ± 0.437  6 0.639 0.445 0.477 0.520 ± 0.104  8 0.146 0.137 0.227  0.170 ± 0.0496 24 No Peak No Peak No Peak n/a Value in italics is below the lower limit of quantitation (BLQ, 0.2 ng/mL) but was included in calculations. BLQ denotes below the lower limit of quantitation (0.2 ng/mL). n/a denotes not applicable.

TABLE 29B Summary of plasma PK parameters for psilocin following 3 mg/kg oral administration of C(I)^(a). Parameter estimate for each animal Parameter M43 M44 M45 Mean ± SD t_(max) (h) 1.00 0.500 0.250 0.583 ± 0.382 C_(max) (ng/mL) 8.13 12.7 17.1 12.6 ± 4.49 C_(max)/Dose^(a) 2.71 4.23 5.70 4.21 ± 1.50 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.45 1.71 1.64  1.60 ± 0.135 AUC_(0-tlast) (h*ng/mL) 17.7 17.6 21.8 19.0 ± 2.38 AUC_(0-tlast)/Dose^(a) 5.92 5.85 7.26  6.34 ± 0.793 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 18.1 17.9 22.3 19.4 ± 2.50 MRT_(0-inf) (h) 2.04 1.65 1.90  1.86 ± 0.197 ^(a)C(I) dose.

TABLE 30A Plasma concentrations of psilocin following 10 mg/kg oral administration of C(I). Experimental Plasma concentration (ng/mL) time (h) M46 M47 M48 Mean ± SD  0.25 41.5 21.0 23.8 28.8 ± 11.1  0.5 40.3 43.0 55.1 46.1 ± 7.88  1 22.9 25.0 32.9 26.9 ± 5.27  2 9.19 5.73 11.8 8.91 ± 3.04  4 3.20 3.09 4.97 3.75 ± 1.06  6 1.63 2.35 1.13  1.70 ± 0.613  8 1.19 2.57 0.867  1.54 ± 0.905 24 BLQ BLQ BLQ n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). n/a denotes not applicable.

TABLE 30B Summary of plasma PK parameters for psilocin following 10 mg/kg oral administration of C(I)^(a). Parameter estimate for each animal Parameter M46 M47 M48 Mean ± SD t_(max) (h) 0.250 0.500 0.500 0.417 ± 0.144 C_(max) (ng/mL) 41.5 43.0 55.1 46.5 ± 7.46 C_(max)/Dose^(a) 4.15 4.30 5.51  4.65 ± 0.746 (kg*ng/mL/mg) Apparent t_(1/2) (h)^(b) 2.80 nc^(c) 1.49 2.15 (n = 2) AUC_(0-tlast) (h*ng/mL) 64.6 59.2 77.9 67.2 ± 9.63 AUC_(0-tlast)/Dose^(a) 6.46 5.92 7.79  6.72 ± 0.963 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 69.4 n/a^(d) 79.8 74.6 (n = 2) MRT_(0-inf) (h) 2.45 n/a  1.91 2.18 (n = 2) ^(a)C(I) dose. ^(b)For M46, apparent t_(1/2) estimate may not be accurate; sampling interval during the terminal phase <2 × t_(1/2). ^(c)nc denotes not calculable as the terminal phase is not well defined. ^(d)n/a denotes not applicable.

TABLE 31 Comparative summary of psilocin pharmacokinetic (PK) parameters following intravenous (IV) dosing of psilocybin or compound C(I)^(a). Parameter Psilocybin C(I)^(b) Nominal prodrug 1 1 dose (mg/kg) t_(max) (h)  0.139 ± 0.0962 0.0833 ± 0.00  C_(max) (ng/mL)  105 ± 19.8 22.3 ± 24.9 C_(max)/Dose^(a)  105 ± 19.8 22.3 ± 24.9 (kg*ng/mL/mg) Apparent t_(1/2) (h) 0.905 (n = 1)  1.23 ± 0.349 AUC_(0-tlast) (h*ng/mL) 89.8 ± 17.5 23.2 ± 21.4 AUC_(0-tlast)/Dose^(a) 89.8 ± 17.5 23.2 ± 21.4 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL)   110 (n = 1) 23.7 ± 21.5 MRT_(0-inf) (h)  1.64 (n = 1)  1.41 ± 0.103 ^(a)C(I) dose ^(b)Values did not exclude possible outlier M37

TABLE 32 Comparative summary of psilocin pharmacokinetic (PK) parameters following oral (PO) dosing of psilocybin or compound C(l). Parameter Psilocybin C(I) Nominal prodrug 1 3 10 1 3 10 dose (mg/kg) t_(max) (h) 0.333 ± 0.144 0.417 ± 0.144 0.333 ± 0.144 0.500 ± 0.00  0.417 ± 0.144 0.417 ± 0.144 C_(max) (ng/mL) 53.7 ± 3.50 52.9 ± 10.5  243 ± 43.7 0.877 ± 0.376  2.15 ± 0.195 8.40 ± 2.17 C_(max)/Dose^(a) 1.56 17.6 ± 3.48 24.3 ± 4.37 0.877 ± 0.376  0.717 ± 0.0651 0.840 ± 0.217 (kg*ng/mL/mg) Apparent t_(1/2) (h) 2.15 (n = 1) 4.51 (n = 2)  3.58 ± 0.920 nc^(a) 3.01 (n = 1) 1.31 (n = 2) AUC_(0-tlast) 67.1 ± 1.61 84.4 ± 10.8  397 ± 55.5 1.34 ± 1.02  5.54 ± 0.330 18.7 ± 4.25 (h*ng/mL) AUC_(0-tlast)/Dose^(a) 34.4 ± 2.24 28.1 ± 3.61 39.7 ± 5.55 1.34 ± 1.02  1.85 ± 0.110  1.87 ± 0.425 (h*kg*ng/mL/mg) AUC_(0-inf) 70.4 (n = 1) 80.5 (n = 2)  398 ± 55.1 n/a^(b) 6.87 (n = 1) 20.2 (n = 2) (h*ng/mL) MRT_(0-inf) (h) 1.53 (n = 1) 2.04 (n = 2)  2.39 ± 0.236 n/a 4.12 (n = 1) 2.53 (n = 2) ^(a)nc denotes not calculable. ^(b)n/a denotes not applicable.

TABLE 33A Summary of mean plasma exposure of psilocin as a function of C(I) dose. C(I) dose 1 mg/kg 1 mg/kg 3 mg/kg 10 mg/kg Parameter i.v. p.o. p.o. p.o. C_(max)/Dose^(a) 22.3 ± 24.9  2.68 ± 0.117 4.21 ± 1.50  4.65 ± 0.746 (kg*ng/mL/mg) Apparent t_(1/2) (h)  1.23 ± 0.349  2.09 ± 0.432  1.60 ± 0.135 2.15 (n = 2) AUC_(0-tlast)/Dose^(a) 23.2 ± 21.4 6.38 ± 1.21  6.34 ± 0.793  6.72 ± 0.963 (h*kg*ng/mL/mg)

In Vitro Survey of Pharmacological Interaction Profiles at Receptors, Transporters and Enzymes Linked to Targeted Health Conditions.

All assays were performed as described in Example 1, except compound C(I) was used in place of C(V). To assess assay performance and establish positive control benchmarks, ligands listed in Table 33B were evaluated alongside test derivative. Results for all assays using compound C(I) or positive controls are shown in Table 33B.

TABLE 33 Data summary table of target assays for compound C(I) and control ligands. Potency (EC₅₀ or IC₅₀) is provided in units of μM. AGN, agonist; ANT, antagonist; OP, opener; BL, blocker; IN, inhibitor. Target name Target type Assay type EC₅₀ (control) IC₅₀ (control) EC₅₀ (C-I) IC₅₀ (C-I) ADRA1A GPCR AGN 5.00E−05 — >100 — ADRA1A GPCR ANT — 9.60E−04 — 6.59 ADRA2A GPCR AGN 4.00E−05 — >100 — ADRA2A GPCR ANT — 3.10E−03 — 18.41 AVPR1A GPCR AGN 4.20E−04 — >100 — AVPR1A GPCR ANT — 1.60E−03 — >100 CHRM1 GPCR AGN 9.70E−03 — >100 — CHRM1 GPCR ANT — 6.10E−03 — 22.89 CHRM2 GPCR AGN 2.70E−02 — >100 — CHRM2 GPCR ANT — 3.20E−03 — 48.88 CNR1 GPCR AGN 1.00E−05 — 54.23 — CNR1 GPCR ANT — 6.20E−04 — >100 DRD1 GPCR AGN 9.10E−02 — >100 — DRD1 GPCR ANT — 7.10E−04 — 24.48 DRD2S GPCR AGN 5.10E−04 — 83.39 — DRD2S GPCR ANT — 9.60E−04 — 91.12 HTR1A GPCR AGN 1.70E−03 — >100 — HTR1A GPCR ANT — 4.60E−02 — >100 HTR1B GPCR AGN 9.00E−05 — 2.14 — HTR1B GPCR ANT — 5.80E−03 — >100 HTR2B GPCR AGN 6.30E−04 — >100 — HTR2B GPCR ANT — 4.00E−04 — 4.94 OPRD1 GPCR AGN 5.00E−05 — >100 — OPRD1 GPCR ANT — 5.80E−04 — >100 GABAA Ion channel OP 6.2 — >100 — GABAA Ion channel BL — 4.6 — >100 HTR3A Ion channel OP 3.00E−01 — >100 — HTR3A Ion channel BL — 1.90E−03 — 7.52 MAO-A Enzyme IN — 2.90E−03 — >100 DAT transporter BL — 1.40E−03 — 42.45 NET transporter BL — 6.70E−03 — 46.99 SERT transporter BL — 1.80E−03 — >100 NMDAR Ion channel BL — 8.00E−02 — >100 NMDAR Ion channel OP 4.40E−01 — >100 —

Example 7—Synthesis and Analysis of a Seventh C₄-Carboxylic Acid-Substituted Tryptamine Derivative

The synthesis of psilocin (1) has been described previously (Shirota et al., J. Nat. Prod. 2003, 66:885-887; Kargbo et al., ACS Omega 2020, 5:16959-16966). Referring to FIG. 9A, to a solution of 1 (74.7 mg, 366 μmol) and N,N-Diisopropylethylamine (100 μL, 574 μmol) in DCM (2 mL) was added, in a dropwise manner, a solution of 2,3-dihydrobenzo[b][1,4]dioxine-5-carbonyl chloride (77.2 mg, 373 μmol) in DCM (1 mL). The mixture was left to react at RT. After 3 hours the mixture contained very little starting material and the reaction mixture was poured into a separatory funnel containing 10 mL of water and 10 mL DCM. The aqueous phase was extracted with DCM (3×10 mL), all organic phases were combined, washed with brine and dried over magnesium sulfate. After filtration the solvent was removed under reduced pressure leaving a beige solid material. The product was purified with flash chromatography (9:1 DCM:MeOH) to yield the desired product (68 mg, 51%) as a white powder. Product 2 was confirmed using the following data: MS-ESI: calculated: 367.1652; observed: 367.1651 m/z [M+H]⁺ ¹H NMR (400 MHz, DMSO) δ 11.06 (s, 1H), 7.57 (dd, J=7.8, 1.6 Hz, 1H), 7.26 (dd, J=8.1, 0.8 Hz, 1H), 7.20-7.13 (m, 2H), 7.07 (t, J=7.9 Hz, 1H), 6.98 (t, J=7.9 Hz, 1H), 6.74 (dd, J=7.6, 0.8 Hz, 1H), 4.38-4.28 (m, 4H), 2.79-2.71 (m, 2H), 2.44 (dd, J=9.2, 6.7 Hz, 2H), 2.01 (s, 6H). Purity was assessed at 95%. It is noted that compound (2) in FIG. 9A corresponds with a compound having chemical formula C(XX):

Assessment of Cell Viability Upon Treatment of a Psilocin Derivative.

Cell viability was assessed as described for Example 1, except the compound with formula C(XX) was evaluated in place of the compound with formula C(V). Data acquired for the derivative having chemical formula C(XX) is displayed as “C-XX” on the x-axes in FIG. 9B and FIG. 9C.

Radioligand Receptor Binding Assays.

Activity at 5-HT_(2A) receptor was assessed as described for Example 1, except the compound with formula C(XX) was evaluated in place of the compound with formula C(V). FIG. 9D shows radioligand competition assay results for compound with formula C(XX), depicted on the x-axis simply as “C-XX”.

Cell Lines and Control Ligands Used to Assess Activity at 5-HT_(IA).

Cell lines, cell line maintenance, and experimental procedures assessing modulation of 5-HT_(1A) were performed as described in Example 1, except that compound C(XX) was evaluated in place of compound C(V). 5-HT_(1A) receptor binding evaluation for compound with formula C(XX) (designated simply “C-XX” along the x-axis) is shown in FIG. 9E. Comparison of data acquired in +5-HT_(1A) cultures with those acquired in −5-HT_(1A) cultures suggests significant receptor modulation.

Evaluation of Metabolic Stability in Human Intestine, Liver, and Serum Fractions In Vitro.

Evaluations of metabolic stability and capacity of novel molecules to release psilocin under various in vitro conditions were performed as described in Example 1, except that compound C(XX) was used in place of compound C(V) for all experiments. FIGS. 9F (i) and 9(F) (ii) show the metabolic stability curves for compound with formula C(XX), designated “C-XX” in assays containing HLM (Panel A), HLS9 (Panel B), HIM (Panel C), HIS9 (Panel D), AB serum (Panel E) and Buffer (Panel F).

In Vivo Evaluation of 5-HT_(2A) Receptor Agonism in Mice.

Evaluation of in vivo HTR was conducted as described in Example 1, except that compound C(XX) was used in place of compound C(V). Elevated incidences of HTR within the defined period of monitoring was observed in (1) psilocybin-treated mice, and (2) those treated with compound “C-XX,” relative to control mice treated with i.p. injected vehicle (0.9% NaCl). These results are illustrated in FIG. 9G, wherein compound with formula C(XX) is designated “C-XX.”

Mouse Pharmacokinetic (PK) Evaluation of Drug Metabolism to Psilocin.

Pharmacokinetic (PK) evaluations were performed in the same manner as described in Example 1, except compound C(XX) was used in place of compound C(V). Results for compound C(XX) PK following C(XX) administration are found in Tables 34A-34B (1 mg/kg IV dose), Tables 35-35B (1 mg/kg oral dose), Tables 36A-36B (3 mg/kg oral dose), Tables 37A-37B (10 mg/kg oral dose), Table 38 (C(XX) exposure), and FIG. 9H. Results for psilocin PK following C(XX) administration are found in Tables 39A-39B (1 mg/kg IV dose), Tables 40A-40B (1 mg/kg oral dose), Tables 41A-41B (3 mg/kg oral dose), Tables 42A-42B (10 mg/kg oral dose), Table 43 (comparative summary for IV data), Table 44 (comparative summary for oral data), Table 45A (psilocin exposure) and FIGS. 9I (i)-9 (ii).

TABLE 34A Plasma concentrations of C(XX) following 1 mg/kg i.v. administration of C(XX). Experimental Plasma concentration (ng/mL) time (h) M49 M50 M51 Mean ± SD 0.0833 109 152 105 122 ± 26.1 0.25 66.5 84.7 60.3 70.5 ± 12.7 0.5 26.1 37.9 32.1 32.0 ± 5.90 1 8.93 8.13 8.22  8.43 ± 0.438 2 0.968 1.03 1.14  1.05 ± 0.0871 4 0.257 0.137 0.148  0.181 ± 0.0663 6 BLQ BLQ BLQ n/a 8 BLQ No No n/a Peak Peak Values in italics are below the lower limit of quantitation (BLQ, 0.25 ng/mL) but were included in calculations. BLQ denotes below the lower limit of quantitation (0.25 ng/mL). n/a denotes not applicable.

TABLE 34B Summary of plasma PK parameters for C(XX) following 1 mg/kg i.v. administration of C(XX). Parameter estimate for each animal Parameter M49 M50 M51 Mean ± SD C₀ (ng/mL) 140 204 139  161 ± 37.3 Apparent t_(1/2) (h) 0.625 0.529 0.536  0.563 ± 0.0538 AUC_(0-tlast) (h*ng/mL) 48.1 62.4 48.0 52.8 ± 8.30 AUC_(0-tlast)/Dose 48.1 62.4 48.0 52.8 ± 8.30 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 48.3 62.5 48.1 53.0 ± 8.26 AUC_(0-inf)/Dose 48.3 62.5 48.1 53.0 ± 8.26 (h*kg*ng/mL/mg) CL (mL/h/kg) 20692 15991 20777 19200 ± 2740  MRT_(0-inf) (h) 0.436 0.367 0.429  0.411 ± 0.0379 V_(ss) (mL/kg) 9026 5874 8913 7940 ± 1790

TABLE 35A Plasma concentrations of C(XX) following 1 mg/kg oral administration of C(XX). Experimental Plasma concentration (ng/mL) time (h) M52 M53 M54 Mean ± SD  0.25 0.701 0.459 0.648 0.603 ± 0.127  0.5 0.702 0.509 0.648  0.620 ± 0.0996  1 0.396 0.286 0.199  0.294 ± 0.0987  2 BLQ BLQ BLQ n/a  4 BLQ BLQ BLQ n/a  6 No Peak No Peak BLQ n/a  8 No Peak BLQ No Peak n/a 24 No Peak No Peak No Peak n/a BLQ denotes below the lower limit of quantitation (0.25 ng/mL). n/a denotes not applicable.

TABLE 35B Summary of plasma PK parameters for C(XX) following 1 mg/kg oral administration of C(XX). Parameter estimate for each animal Parameter M52 M53 M54 Mean ± SD t_(max) (h) 0.500 0.500 0.250 0.417 ± 0.144 C_(max) (ng/mL) 0.702 0.509 0.648  0.620 ± 0.0996 C_(max)/Dose 0.702 0.509 0.648  0.620 ± 0.0996 (kg*ng/mL/mg)

TABLE 36A Plasma concentrations of C(XX) following 3 mg/kg oral administration of C(XX). Experimental Plasma concentration (ng/mL) time (h) M55 M56 M57 Mean ± SD  0.25 1.49 1.72 1.93  1.71 ± 0.220  0.5 1.45 1.13 1.43  1.34 ± 0.179  1 0.430 0.752 0.535 0.572 ± 0.164  2 0.124 0.244 0.156  0.175 ± 0.0621  4 No Peak BLQ No Peak n/a  6 No Peak BLQ BLQ n/a  8 No Peak BLQ BLQ n/a 24 No Peak No Peak No Peak n/a Values in italics are below the lower limit of quantitation (BLQ, 0.25 ng/mL) but were included in calculations. BLQ denotes below the lower limit of quantitation (0.25 ng/mL). n/a denotes not applicable.

TABLE 36B Summary of plasma PK parameters for C(XX) following 3 mg/kg oral administration of C(XX). Parameter estimate for each animal Parameter M55 M56 M57 Mean ± SD t_(max) (h) 0.250 0.250 0.250 0.250 ± 0.00  C_(max) (ng/mL) 1.49 1.72 1.93  1.71 ± 0.220 C_(max)/Dose 0.497 0.573 0.643  0.571 ± 0.0734 (kg*ng/mL/mg) Apparent t_(1/2) (h) 0.438 0.669 0.481 0.529 ± 0.123 AUC_(0-tlast) (h*ng/mL) 1.22 1.48 1.42  1.37 ± 0.137 AUC_(0-tlast)/Dose 0.406 0.494 0.474  0.458 ± 0.0457 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 1.30 1.72 1.53  1.51 ± 0.210 AUC_(0-inf)/Dose 0.433 0.572 0.510  0.505 ± 0.0700 (h*kg*ng/mL/mg) MRT_(0-inf) (h) 0.793 1.08 0.823 0.899 ± 0.158 F(%) 0.816 1.08 0.962 0.953 ± 0.132

TABLE 37A Plasma concentrations of C(XX) following 10 mg/kg oral administration of C(XX). Experimental Plasma concentration (ng/mL) time (h) M58 M59 M60 Mean ± SD  0.25 2.99 9.12 10.3 7.47 ± 3.92  0.5 2.79 3.87 5.79 4.15 ± 1.52  1 1.53 1.69 2.74  1.99 ± 0.657  2 0.707 0.533 1.08 0.773 ± 0.279  4 0.225 BLQ 0.302 0.264 (n = 2)  6 0.524 BLQ 0.196 0.360 (n = 2)  8 0.335 BLQ 0.185 0.260 (n = 2) 24 No Peak No Peak No Peak n/a Values in italics are below the lower limit of quantitation (BLQ, 0.25 ng/mL) but were included in calculations. BLQ denotes below the lower limit of quantitation (0.25 ng/mL). n/a denotes not applicable.

TABLE 37B Summary of plasma PK parameters for C(XX) following 10 mg/kg oral administration of C(XX). Parameter estimate for each animal Parameter M58 M59 M60 Mean ± SD t_(max) (h) 0.250 0.250 0.250 0.250 ± 0.00  C_(max) (ng/mL) 2.99 9.12 10.3 7.47 ± 3.92 C_(max)/Dose 0.299 0.912 1.03 0.747 ± 0.392 (kg*ng/mL/mg) Apparent t_(1/2) (h)^(a) nc^(b) 0.534 5.66 3.10 (n = 2) AUC_(0-tlast) (h*ng/mL) 5.65 4.99 9.16 6.60 ± 2.24 AUC_(0-tlast)/Dose 0.565 0.499 0.916 0.660 ± 0.224 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) n/a^(c) 5.40 10.7 8.03 (n = 2) MRT_(0-inf) (h) n/a 0.800 3.56 2.18 (n = 2) F(%)^(d) 1.07 0.941 1.73  1.24 ± 0.423 ^(a)For M60, apparent t_(1/2) estimate may not be accurate; sampling interval during the terminal phase <2 × t_(1/2). ^(b)nc denotes not calculable as the terminal phase is not well defined. ^(c)n/a denotes not applicable. ^(d)AUC_(0-tlast) was used for p.o. group, thus value might be under-estimated.

TABLE 38 Summary of mean plasma exposure of C(XX) as a function of dose. C(XX)dose Parameter 1 mg/kg i.v. 1 mg/kg p.o. 3 mg/kg p.o. 10 mg/kg p.o. C_(max)/Dose n/a^(a) 0.620 ± 0.0996  0.571 ± 0.0734 0.747 ± 0.392 (kg*ng/mL/mg) Apparent t_(1/2) (h)  0.563 ± 0.0538 nc^(b) 0.529 ± 0.123 3.10 (n = 2) AUC_(0-tlast)/Dose 52.8 ± 8.30 n/a  0.458 ± 0.0457 0.660 ± 0.224 (h*kg*ng/mL/mg) F(%) n/a n/a 0.953 ± 0.132  1.24 ± 0.423 ^(a)n/a denotes not applicable. ^(b)nc denotes not calculable as the terminal phase is not well defined.

TABLE 39A Plasma concentrations of psilocin following 1 mg/kg i.v. administration of C(XX). Experimental Plasma concentration (ng/mL) time (h) M49 M50 M51 Mean ± SD 0.0833 19.9 25.3 21.3 22.2 ± 2.80 0.25 23.4 29.4 20.4 24.4 ± 4.58 0.5 18.0 21.9 27.3 22.4 ± 4.67 1 11.4 10.2 10.3  10.6 ± 0.666 2 6.65 3.26 4.32 4.74 ± 1.73 4 0.816 0.803 0.536 0.718 ± 0.158 6 0.266 0.250 0.298  0.271 ± 0.0244 8 BLQ BLQ BLQ n/a Values in italics are below the lower limit of quantitation (BLQ, 0.5 ng/mL) but were included in calculations. BLQ denotes below the lower limit of quantitation (0.5 ng/mL). n/a denotes not applicable.

TABLE 39B Summary of plasma PK parameters for psilocin following 1 mg/kg i.v. administration of C(XX). Parameter estimate for each animal Parameter M49 M50 M51 Mean ± SD t_(max) (h) 0.250 0.250 0.500 0.333 ± 0.144 C_(max) (ng/mL) 23.4 29.4 27.3 26.7 ± 3.04 C_(max)/Dose^(a) 23.4 29.4 27.3 26.7 ± 3.04 (kg*ng/mL/mg) Apparent t_(1/2) (h) 0.861 1.08 1.04 0.993 ± 0.116 AUC_(0-tlast) (h*ng/mL) 32.2 30.2 30.4 30.9 ± 1.10 AUC_(0-tlast)/Dose^(a) 32.2 30.2 30.4 30.9 ± 1.10 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 32.5 30.6 30.8 31.3 ± 1.05 MRT_(0-inf) (h) 1.31 1.13 1.17  1.20 ± 0.0971

TABLE 40A Plasma concentrations of psilocin following 1 mg/kg oral administration of C(XX). Experimental Plasma concentration (ng/mL) time (h) M52 M53 M54 Mean ± SD  0.25 20.2 6.94 6.76 11.3 ± 7.71  0.5 18.8 13.7 11.0 14.5 ± 3.96  1 14.0 10.5 6.59 10.4 ± 3.71  2 4.40 3.29 3.78  3.82 ± 0.556  4 1.21 0.829 0.717 0.919 ± 0.258  6 0.306 0.604 0.699 0.536 ± 0.205  8 0.260 0.280 0.223  0.254 ± 0.0289 24 BLQ BLQ BLQ n/a Values in italics are below the lower limit of quantitation (BLQ, 0.5 ng/mL) but were included in calculations. BLQ denotes below the lower limit of quantitation (0.5 ng/mL). n/a denotes not applicable.

TABLE 40B Summary of plasma PK parameters for psilocin following 1 mg/kg oral administration of C(XX). Parameter estimate for each animal Parameter M52 M53 M54 Mean ± SD t_(max) (h) 0.250 0.500 0.500 0.417 ± 0.144 C_(max) (ng/mL) 20.2 13.7 11.0 15.0 ± 4.73 C_(max)/Dose^(a) 20.2 13.7 11.0 15.0 ± 4.73 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.80 1.80 1.63   1.74 ± 0.0999 AUC_(0-tlast) (h*ng/mL) 30.7 21.5 18.4 23.5 ± 6.39 AUC_(0-tlast)/Dose^(a) 30.7 21.5 18.4 23.5 ± 6.39 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 31.3 22.2 18.9 24.1 ± 6.44 MRT_(0-inf) (h) 1.64 2.02 2.11  1.92 ± 0.251

TABLE 41A Plasma concentrations of psilocin following 3 mg/kg oral administration of C(XX). Experimental Plasma concentration (ng/mL) time (h) M55 M56 M57 Mean ± SD  0.25 28.7 22.0 34.7 28.5 ± 6.35  0.5 29.2 24.0 29.2 27.5 ± 3.00  1 13.9 21.0 14.3 16.4 ± 3.99  2 7.27 7.83 7.13  7.41 ± 0.370  4 1.13 3.08 1.15 1.79 ± 1.12  6 0.786 1.28 1.14  1.07 ± 0.255  8 0.486 0.440 1.26 0.729 ± 0.461 24 BLQ BLQ BLQ n/a Values in italics are below the lower limit of quantitation (BLQ, 0.5 ng/mL) but were included in calculations. n/a denotes not applicable.

TABLE 41B Summary of plasma PK parameters for psilocin following 3 mg/kg oral administration of C(XX). Parameter estimate for each animal Parameter M55 M56 M57 Mean ± SD t_(max) (h) 0.500 0.500 0.250 0.417 ± 0.144 C_(max) (ng/mL) 29.2 24.0 34.7 29.3 ± 5.35 C_(max)/Dose^(a) 9.73 8.00 11.6 9.77 ± 1.78 (kg*ng/mL/mg) Apparent t_(1/2) (h)^(b) 3.29 1.46 nc^(c) 2.37 (n = 2) AUC_(0-tlast) (h*ng/mL) 41.1 48.9 44.3 44.8 ± 3.94 AUC_(0-tlast)/Dose^(a) 13.7 16.3 14.8 14.9 ± 1.31 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL) 43.4 49.9 n/a^(d) 46.6 (n = 2) MRT_(0-inf) (h) 2.10 1.99 n/a 2.04 (n = 2) ^(b)For M55, apparent t_(1/2) estimate may not be accurate; sampling interval during the terminal phase <2 × t_(1/2). ^(c)nc denotes not calculable as the terminal phase is not well defined. ^(d)n/a denotes not applicable.

TABLE 42A Plasma concentrations of psilocin following 10 mg/kg oral administration of C(XX). Experimental Plasma concentration (ng/mL) time (h) M58 M59 M60 Mean ± SD  0.25 52.6 173 120  115 ± 60.3  0.5 54.2 94.6 151 99.9 ± 48.6  1 46.2 47.2 69.9 54.4 ± 13.4  2 21.7 21.3 41.9 28.3 ± 11.8  4 9.58 5.07 8.73 7.79 ± 2.40  6 8.15 2.07 4.86 5.03 ± 3.04  8 5.65 1.72 3.69 3.69 ± 1.97 24 BLQ BLQ BLQ n/a BLQ denotes below the lower limit of quantitation (0.5 ng/mL). n/a denotes not applicable.

TABLE 42B Summary of plasma PK parameters for psilocin following 10 mg/kg oral administration of C(XX). Parameter estimate for each animal Parameter M58 M59 M60 Mean ± SD t_(max) (h) 0.500 0.250 0.500 0.417 ± 0.144 C_(max) (ng/mL) 54.2 173 151  126 ± 63.2 C_(max)/Dose^(a) 5.42 17.3 15.1 12.6 ± 6.32 (kg*ng/mL/mg) Apparent t_(1/2) (h)^(b) 5.25 2.56 3.22 3.68 ± 1.40 AUC_(0-tlast) (h*ng/mL) 138 154 220  171 ± 43.5 AUC_(0-tlast)/Dose^(a) 13.8 15.4 22.0 17.1 ± 4.35 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL)^(c) 181 160 237  193 ± 39.9 MRT_(0-inf) (h) 5.55 1.78 2.49 3.27 ± 2.01 ^(b)Apparent t_(1/2) estimate may not be accurate; sampling interval during the terminal phase <2 × t_(1/2). ^(c)For M58, % AUC extrapolated from tlast to infinity is >20% (24%), thus estimate is not considered accurate.

TABLE 43 Comparative summary of psilocin pharmacokinetic (PK) parameters following intravenous (IV) dosing of psilocybin or compound C(XX)^(a) _(.) Parameter Psilocybin C(XX) Nominal prodrug dose 1 1 (mg/kg) t_(max) (h)  0.139 ± 0.0962 0.333 ± 0.144 C_(max) (ng/mL)  105 ± 19.8 26.7 ± 3.04 C_(max)/Dose^(a)  105 ± 19.8 26.7 ± 3.04 (kg*ng/mL/mg) Apparent t_(1/2) (h) 0.905 (n = 1) 0.993 ± 0.116 AUC_(0-tlast) (h*ng/mL) 89.8 ± 17.5 30.9 ± 1.10 AUC_(0-tlast)/Dose^(a) 89.8 ± 17.5 30.9 ± 1.10 (h*kg*ng/mL/mg) AUC_(0-inf) (h*ng/mL)   110 (n = 1) 31.3 ± 1.05 MRT_(0-inf) (h)  1.64 (n = 1)  1.20 ± 0.0971 ^(a)C(XX) dose was used. ^(b)nc denotes not calculable.

TABLE 44 Comparative summary of psilocin pharmacokinetic (PK) parameters following oral (PO) dosing of psilocybin or compound C(XX). Parameter Psilocybin C(XX) Nominal prodrug 1 3 10 1 3 10 dose (mg/kg) t_(max) (h) 0.333 ± 0.144 0.417 ± 0.144 0.333 ± 0.144 0.417 ± 0.144 0.417 ± 0.144 0.417 ± 0.144 C_(max) (ng/mL) 53.7 ± 3.50 52.9 ± 10.5  243 ± 43.7 15.0 ± 4.73 29.3 ± 5.35  126 ± 63.2 C_(max)/Dose^(a) 1.56 17.6 ± 3.48 24.3 ± 4.37 15.0 ± 4.73 9.77 ± 1.78 12.6 ± 6.32 (kg*ng/mL/mg) Apparent t_(1/2) (h) 2.15 (n = 1) 4.51 (n = 2)  3.58 ± 0.920  1.74 ± 0.0999 2.37 (n = 2) 3.68 ± 1.40 AUC_(0-tlast) 67.1 ± 1.61 84.4 ± 10.8  397 ± 55.5 23.5 ± 6.39 44.8 ± 3.94  171 ± 43.5 (h*ng/mL) AUC_(0-tlast)/Dose^(a) 34.4 ± 2.24 28.1 ± 3.61 39.7 ± 5.55 23.5 ± 6.39 14.9 ± 1.31 17.1 ± 4.35 (h*kg*ng/mL/mg) AUC_(0-inf) 70.4 (n = 1) 80.5 (n = 2)  398 ± 55.1 24.1 ± 6.44 46.6 (n = 2)  193 ± 39.9 (h*ng/mL) MRT_(0-inf) (h) 1.53 (n = 1) 2.04 (n = 2)  2.39 ± 0.236  1.92 ± 0.251 2.04 (n = 2) 3.27 ± 2.01 ^(a)C(XX) dose was used. ^(b)nc denotes not calculable. ^(c)n/a denotes not applicable.

TABLE 45A Summary of mean plasma exposure of psilocin as a function of C(XX) dose. C(XX)dose Parameter 1 mg/kg i.v. 1 mg/kg p.o. 3 mg/kg p.o. 10 mg/kg p.o. C_(max)/Dose^(a) (kg*ng/mL/mg) 26.7 ± 3.04 15.0 ± 4.73 9.77 ± 1.78 12.6 ± 6.32 Apparent t_(1/2) (h) 0.993 ± 0.116   1.74 ± 0.0999 2.37 (n = 2) 3.68 ± 1.40 AUC_(0-tlast)/Dose^(a) 30.9 ± 1.10 23.5 ± 6.39 14.9 ± 1.31 17.1 ± 4.35 (h*kg*ng/mL/mg)

In Vitro Survey of Pharmacological Interaction Profiles at Receptors, Transporters and Enzymes Linked to Targeted Health Conditions.

All assays were performed as described for Example 1, except compound C(XX) was used in place of C(V). To assess assay performance and establish positive control benchmarks, ligands listed in Table 14B were evaluated alongside test derivative. Results for all assays using compound C(XX) or positive controls are shown in Table 45B.

TABLE 45B Data summary table of target assays for compound C(XX) and control ligands. Potency (EC₅₀ or IC₅₀) is provided in units of μM. AGN, agonist; ANT, antagonist; OP, opener; BL, blocker; IN, inhibitor. Target name Target type Assay type EC₅₀ (control) IC₅₀ (control) EC₅₀ (C-XX) IC₅₀ (C-XX) ADRA1A GPCR AGN 5.00E−05 — >100 — ADRA1A GPCR ANT — 9.60E−04 5.21 ADRA2A GPCR AGN 4.00E−05 — >100 — ADRA2A GPCR ANT — 3.10E−03 — 47.93 AVPR1A GPCR AGN 4.20E−04 — >100 — AVPR1A GPCR ANT — 1.60E−03 — >100 CHRM1 GPCR AGN 9.70E−03 — >100 — CHRM1 GPCR ANT — 6.10E−03 — >100 CHRM2 GPCR AGN 2.70E−02 — >100 — CHRM2 GPCR ANT — 3.20E−03 — >100 CNR1 GPCR AGN 1.00E−05 — >100 — CNR1 GPCR ANT — 6.20E−04 — >100 DRD1 GPCR AGN 9.10E−02 — >100 — DRD1 GPCR ANT — 7.10E−04 — 11.1 DRD2S GPCR AGN 5.10E−04 — 1.72 — DRD2S GPCR ANT — 9.60E−04 — >100 HTR1A GPCR AGN 1.70E−03 — 2.03 — HTR1A GPCR ANT — 4.60E−02 — >100 HTR1B GPCR AGN 9.00E−05 — 2.00E−01 — HTR1B GPCR ANT — 5.80E−03 — >100 HTR2B GPCR AGN 6.30E−04 — >100 — HTR2B GPCR ANT — 4.00E−04 — 1.60E−02 OPRD1 GPCR AGN 5.00E−05 — >100 — OPRD1 GPCR ANT — 5.80E−04 — >100 GABAA Ion channel OP 6.2 — >100 — GABAA Ion channel BL — 4.6 — >100 HTR3A Ion channel OP 3.00E−01 — >100 — HTR3A Ion channel BL — 1.90E−03 — 3.77 MAO-A Enzyme IN — 2.90E−03 — >100 DAT transporter BL — 1.40E−03 — >100 NET transporter BL — 6.70E−03 — 15.04 SERT transporter BL — 1.80E−03 — 14.7 NMDAR Ion channel BL — 8.00E−02 — >100 NMDAR Ion channel OP 4.40E−01 — >100 —

Example 8—Synthesis and Analysis of an Eighth C₄-Carboxylic Acid-Substituted Tryptamine Derivative

The synthesis of psilocin (1) has been described previously (Shirota et al., J. Nat. Prod. 2003, 66:885-887; Kargbo et al., ACS Omega 2020, 5:16959-16966). Referring to FIG. 10A, a solution of (1) (600 mg, 2.94 mmol) and triethylamine (823 uL, 5.87 mmol) in anhydrous DCM (29.4 mL) was cooled down to 0° C., To it was added cyclopropylacetyl chloride (813 UL, 822 mmol, 2.8 eq) in 3 portions (1.2 eq+1.2 eq+0.4 eq; with 2 hour intervals) and the resulting mixture was warmed up to RT and stirred overnight. After 18 h, TLC (MeOH/DCM 20:80) showed full consumption of psilocin. The reaction was quenched with methanol (1 mL), and the volatiles were removed in vacuo. The crude residue was directly purified by FC chromatography on silica gel (24 g, MeOH/DCM 0:100 to 20:80, product eluting at 15% MeOH) to afford the product as a brown oil, ¹H-NMR showed co-elution of cyclopropylacetic acid with the product. This isolated material was re-dissolved in DCM (25 mL) and extracted with sat'd aq. NaHCO₃ (1×25 mL). The aqueous layer was back extracted with DCM (2×30 mL), washed with brine, dried over anhydrous Na₂SO₄, filtered and concentrated to afford the pure product as a light brown solid (510 mg, 61%). Product (2) was confirmed using the following data: MS-ESI: calculated: 286.16813; observed: 287.17532 m/z [M+H]⁺. ¹H NMR (400 MHz, CDCs) δ 820 (s, 1H), 7.18 (dd, J=8.2, 1.0 Hz, 1H), 7.12 (dd, J=8.2, 7.5 Hz, 1H), 6.94 (dt, J=2.2, 1.0 Hz, 1H), 6.81 (dd, J=7.5, 1.0 Hz, 1H), 2.98-2.86 (m, 2H), 2.64-2.55 (m, 4H), 2.30 (s, 6H), 1.32-1.17 (m, 1H), 0.71-0.59 (m, 2H), 0.31 (dt, J=60, 4.7 Hz, 2H). Purity was assessed at 95%. It is noted that compound (2) in FIG. 10A corresponds to a compound having chemical formula C(IV):

Assessment of Cell Viability Upon Treatment of a Psilocin Derivative.

Cell viability was assessed as described for Example 1, except the compound with formula C(IV) was evaluated in place of the compound with formula C(V). Data acquired for the derivative having chemical formula C(IV) is displayed as “C-IV” on the x-axes in FIG. 10B and FIG. 10C.

Radioligand Receptor Binding Assays.

Activity at 5-HT_(2A) receptor was assessed as described for Example 1, except the compound with formula C(IV) was evaluated in place of the compound with formula C(V). FIG. 10D shows radioligand competition assay results for compound with formula C(IV), depicted on the x-axis simply as “C-IV”.

Cell Lines and Control Ligands Used to Assess Activity at 5-HT_(IA).

Cell lines, cell line maintenance, and experimental procedures assessing modulation of 5-HT_(1A) were performed as described in Example 1, except that compound C(IV) was evaluated in place of compound C(V). 5-HT_(1A) receptor binding evaluation for compound with formula C(IV) (designated simply “C-IV” along the x-axis) is shown in FIG. 10E. Comparison of data acquired in +5-HT_(1A) cultures with those acquired in −5-HT_(1A) cultures suggests significant receptor modulation.

Evaluation of Metabolic Stability in Human Intestine, Liver, and Serum Fractions In Vitro.

Evaluations of metabolic stability and capacity of novel molecules to release psilocin under various in vitro conditions were performed as described in Example 1, except that compound C(IV) was used in place of compound C(V) for all experiments. FIGS. 10F (i) and 10F (ii) show the metabolic stability curves for compound with formula C(IV), designated “C-IV” in assays containing HLM (Panel A), HLS9 (Panel B), HIM (Panel C), HIS9 (Panel D), AB serum (Panel E) and Buffer (Panel F).

In Vivo Evaluation of 5-HT_(2A) Receptor Agonism in Mice.

Evaluation of in vivo HTR was conducted as described in Example 1, except that compound C(IV) was used in place of compound C(V). Elevated incidences of HTR within the defined period of monitoring was observed in (1) psilocybin-treated mice, and (2) those treated with compound “C-IV,” relative to control mice treated with i.p. injected vehicle (0.9% NaCl). These results are illustrated in FIG. 10G, wherein compound with formula C(IV) is designated “C-IV.” Results for control mice injected with vehicle are not shown in FIG. 10G, but are the same as those in Examples 1 and 2 since HTR experiments were run with the same control cohorts.

Mouse Pharmacokinetic (PK) Evaluation of Drug Metabolism to Psilocin.

Pharmacokinetic (PK) evaluations were performed in the same manner as described in Example 1, except compound C(IV) was used in place of compound C(V). Notably, compound C(IV) was not detectable in any animals at any dose, suggesting a degree of instability and/or quick conversion to psilocin. Thus, only psilocin PK analysis was performed. Furthermore, “measured” concentrations of C(IV) dosing solutions were used in place of “nominal” concentrations, to minimize variance owing to compound instability in dosing solutions. Table 46 summarizes these “measured” concentrations along with corresponding “nominal” concentrations for each dosing solution. Results for psilocin PK following C(IV) administration are found in Tables 47A-47B (0.293 mg/kg IV dose), Tables 48A-48B (0.275 mg/kg oral dose), Tables 49A 49B (0.789 mg/kg oral dose), Tables 50A-50B (2.52 mg/kg oral dose), Table 51 (comparative summary for IV data), Table 52 (comparative summary for oral data), Table 53A (psilocin exposure) and FIGS. 10H (i) and 10H (ii).

TABLE 46 C(IV) and psilocin residual dosing solution concentrations^(a). C(IV), C(IV), C(IV), Psilocin^(b), nominal measured administered measured (mg/mL) (mg/mL) dose^(c) (mg/kg) (mg/mL) 0.2 0.0586 0.293 0.00324 0.1 0.0275 0.275 0.001740 0.3 0.0789 0.789 0.00474 1 0.252 2.52 0.0234 ^(a)C(IV) dosing solutions were diluted 4000-fold prior to analysis. ^(b)Psilocin was also observed in the bioanalytical standard ^(c)Administered dose (measured concentration * dose volume). ^(d)Levels are not accurate as psilocin peak areas in the dosing solution were below the lower limit of quantitation; shown for reference only.

TABLE 47A Plasma concentrations of psilocin following 0.293 mg/kg i.v. administration of C(IV). Experimental Plasma concentration (ng/mL) time (h) M61 M62 M63 Mean ± SD 0.0833 20.5 148 23.8 64.1 ± 72.7 0.25 9.33 57.1 11.1 25.8 ± 27.1 0.5 4.74 18.8 4.68 9.41 ± 8.13 1 1.74 4.66 2.52 2.97 ± 1.51 2 0.932 3.55 0.747 1.74 ± 1.57 4 0.450 0.622 0.181 0.418 ± 0.222 6 0.149 0.308 0.134  0.197 ± 0.0964 8 No Peak BLQ BLQ n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). Values in italics are below the lower limit of quantitation (BLQ, 0.2 ng/mL) but were included in calculations. n/a denotes not applicable.

TABLE 47B Summary of plasma PK parameters for psilocin following 0.293 mg/kg i.v. administration of C(IV). Parameter estimate for each animal Parameter M61 M62 M63 Mean ± SD t_(max) (h) 0.0833 0.0833 0.0833 0.0833 ± 0.00  C_(max) (ng/mL) 20.5 148 23.8 64.1 ± 72.7 C_(max)/Dose^(a) 70.0 505 81.2 219 ± 248 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.51 1.13 1.61  1.42 ± 0.253 AUC_(0-tlast) 9.57 44.1 9.94 21.2 ± 19.8 (h*ng/mL) AUC_(0-tlast)/Dose^(a) 32.7 151 33.9 72.4 ± 67.7 (h*kg*ng/mL/mg) AUC_(0-inf) 9.90 44.6 10.3 21.6 ± 19.9 (h*ng/mL) MRT_(0-inf) (h) 1.32 0.738 1.06  1.04 ± 0.292 ^(a)C(IV) measured dose of 0.293 mg/kg (measured concentration * dose volume) was used.

TABLE 48A Plasma concentrations of psilocin following 0.275 mg/kg oral administration of C(IV). Experimental Plasma concentration (ng/mL) time (h) M64 M65 M66 Mean ± SD  0.25 5.39 10.0 9.62 8.33 ± 2.56  0.5 4.88 6.05 3.61 4.85 ± 1.22  1 2.94 4.50 1.50 2.98 ± 1.50  2 0.851 0.862 0.827  0.847 ± 0.0179  4 0.233 0.254 BLQ  0.244 ± 0.0148  6 0.166 0.106 BLQ 0.136 (n = 2)  8 BLQ 0.109 BLQ 0.109 (n = 1) 24 No Peak No Peak No Peak n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). Values in italics are below the lower limit of quantitation (BLQ, 0.2 ng/mL) but were included in calculations. n/a denotes not applicable.

TABLE 48B Summary of plasma PK parameters for psilocin following 0.275 mg/kg oral administration of C(IV). Parameter estimate for each animal Parameter M64 M65 M66 Mean ± SD t_(max) (h) 0.250 0.250 0.250 0.250 ± 0.00  C_(max) (ng/mL) 5.39 10.0 9.62 8.34 ± 2.56 C_(max)/Dose^(a) 19.6 36.4 35.0 30.3 ± 9.31 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.70 1.96 0.748  1.47 ± 0.637 AUC_(0-tlast) 6.91 9.58 5.07 7.19 ± 2.27 (h*ng/mL) AUC_(0-tlast)/Dose^(a) 25.1 34.9 18.4 26.1 ± 8.26 (h*kg*ng/mL/mg) AUC_(0-inf) 7.31 9.89 5.96 7.72 ± 2.00 (h*ng/mL) MRT_(0-inf) (h) 1.70 1.54 1.02  1.42 ± 0.356 ^(a)C(IV) measured dose of 0.275 mg/kg (measured concentration * dose volume) was used.

TABLE 49A Plasma concentrations of psilocin following 0.789 mg/kg oral administration of C(IV). Experimental Plasma concentration (ng/mL) time (h) M67 M68 M69 Mean ± SD  0.25 8.80 10.1 12.4 10.4 ± 1.82  0.5 16.2 8.35 12.6 12.4 ± 3.93  1 4.32 4.90 4.55  4.59 ± 0.292  2 1.46 1.97 1.84  1.76 ± 0.265  4 0.356 0.354 0.393  0.368 ± 0.0220  6 0.120 0.140 0.178  0.146 ± 0.0295  8 0.118 0.126 BLQ 0.122 (n = 2) 24 No Peak No Peak No Peak n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). Values in italics are below the lower limit of quantitation (BLQ, 0.2 ng/mL) but were included in calculations. n/a denotes not applicable.

TABLE 49B Summary of plasma PK parameters for psilocin following 0.789 mg/kg oral administration of C(IV). Parameter estimate for each animal Parameter M67 M68 M69 Mean ± SD t_(max) (h) 0.500 0.250 0.500 0.417 ± 0.144 C_(max) (ng/mL) 16.2 10.1 12.6 13.0 ± 3.07 C_(max)/Dose^(a) 20.5 12.8 16.0 16.4 ± 3.89 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.61 1.51 1.19  1.43 ± 0.219 AUC_(0-tlast) 13.6 12.6 14.0  13.4 ± 0.723 (h*ng/mL) AUC_(0-tlast)/Dose^(a) 17.2 16.0 17.8  17.0 ± 0.916 (h*kg*ng/mL/mg) AUC_(0-inf) 13.9 12.9 14.3  13.7 ± 0.736 (h*ng/mL) MRT_(0-inf) (h) 1.39 1.56 1.31  1.42 ± 0.128 ^(a)C(IV) measured dose of 0.789 mg/kg (measured concentration * dose volume) was used.

TABLE 50A Plasma concentrations of psilocin following 2.52 mg/kg oral administration of C(IV). Experimental Plasma concentration (ng/mL) time (h) M70 M71 M72 Mean ± SD  0.25 58.5 47.6 51.8 52.6 ± 5.50  0.5 44.3 33.9 52.2 43.5 ± 9.18  1 31.8 15.8 18.7 22.1 ± 8.52  2 5.54 4.10 7.20 5.61 ± 1.55  4 1.03 0.758 1.19 0.993 ± 0.218  6 0.375 0.397 0.372  0.381 ± 0.0137  8 0.256 0.188 0.184  0.209 ± 0.0405 24 BLQ No Peak No Peak n/a BLQ denotes below the lower limit of quantitation (0.2 ng/mL). Values in italics are below the lower limit of quantitation (BLQ, 0.2 ng/mL) but were included in calculations. n/a denotes not applicable.

TABLE 50B Summary of plasma PK parameters for psilocin following 2.52 mg/kg oral administration of C(IV). Parameter estimate for each animal Parameter M70 M71 M72 Mean ± SD t_(max) (h) 0.250 0.250 0.500 0.333 ± 0.144 C_(max) (ng/mL) 58.5 47.6 52.2 52.8 ± 5.47 C_(max)/Dose^(a) 23.2 18.9 20.7 20.9 ± 2.17 (kg*ng/mL/mg) Apparent t_(1/2) (h) 1.99 1.99 1.49  1.82 ± 0.291 AUC_(0-tlast) 61.2 42.2 56.5 53.3 ± 9.90 (h*ng/mL) AUC_(0-tlast)/Dose^(a) 24.3 16.7 22.4 21.2 ± 3.93 (h*kg*ng/mL/mg) AUC_(0-inf) 62.0 42.7 56.9 53.9 ± 9.96 (h*ng/mL) MRT_(0-inf) (h) 1.20 1.21 1.19   1.20 ± 0.0102 ^(a)C(IV) measured dose of 2.52 mg/kg (measured concentration * dose volume) was used.

TABLE 51 Psilocin PK parameters following IV prodrug dosing. Parameter Psilocybin C(IV) Prodrug nominal 1 1 dose (mg/kg) Prodrug measured 1 0.293 dose (mg/kg)^(a) t_(max) (h)  0.139 ± 0.0962 0.0833 ± 0.00  C_(max) (ng/mL)  105 ± 19.8 64.1 ± 72.7 C_(max)/Dose^(b) _(nominal)  105 ± 19.8 64.1 ± 72.7 (kg*ng/mL/mg) C_(max)/Dose^(b) _(measured)  105 ± 19.8 219 ± 248 (kg*ng/mL/mg) Apparent t_(1/2) (h) 0.905 (n = 1)  1.42 ± 0.253 AUC_(0-tlast) 89.8 ± 17.5 21.2 ± 19.8 (h*ng/mL) AUC_(0-tlast)/ 89.8 ± 17.5 21.2 ± 19.8 Dose^(b) _(nominal) (h*kg*ng/mL/mg) AUC_(0-tlast)/ 89.8 ± 17.5 72.4 ± 67.7 Dose^(b) _(measured) (h*kg*ng/mL/mg) AUC_(0-inf) (h * ng/mL)   110 (n = 1) 21.6 ± 19.9 MRT_(0-inf) (h)  1.64 (n = 1)  1.04 ± 0.292

TABLE 52 Psilocin PK parameters following oral prodrug dosing. Parameter Psilocybin C(IV) Prodrug nominal 1 3 10 1 3 10 dose (mg/kg) Prodrug 1.56 3 10 0.275 0.789 2.52 measured dose (mg/kg)^(a) tmax (h) 0.333 ± 0.144 0.417 ± 0.144 0.333 ± 0.144 0.250 ± 0.00  0.417 ± 0.144 0.333 ± 0.144 C_(max) (ng/mL) 53.7 ± 3.50 52.9 ± 10.5  243 ± 43.7 8.34 ± 2.56 13.0 ± 3.07 52.8 ± 5.47 C_(max)/Dose^(b) _(nominal) 1.56 17.6 ± 3.48 24.3 ± 4.37 0.275 4.32 ± 1.02  5.28 ± 0.547 (kg*ng/mL/mg) C_(max)/Dose^(b) _(measured) 34.4 ± 2.24 17.6 ± 3.48 24.3 ± 4.37 30.3 ± 9.31 16.4 ± 3.89 20.9 ± 2.17 (kg*ng/mL/mg) Apparent t_(1/2) (h) 2.15 (n = 1) 4.51 (n = 2)  3.58 ± 0.920  1.47 ± 0.637  1.43 ± 0.219  1.82 ± 0.291 AUC_(0-tlast) 67.1 ± 1.61 84.4 ± 10.8  397 ± 55.5 7.19 ± 2.27  13.4 ± 0.723 53.3 ± 9.90 (h*ng/mL) AUC_(0-tlast)/ 34.4 ± 2.24 28.1 ± 3.61 39.7 ± 5.55 30.3 ± 9.31  4.47 ± 0.241  5.33 ± 0.990 Dose^(b) _(nominal) (h*kg*ng/mL/mg) AUC_(0-tlast)/ 43.0 ± 1.03 28.1 ± 3.61 39.7 ± 5.55 26.1 ± 8.26  17.0 ± 0.916 21.2 ± 3.93 Dose^(b) _(measured) (h*kg*ng/mL/mg) AUC_(0-inf) 70.4 (n = 1) 80.5 (n = 2)  398 ± 55.1 7.72 ± 2.00  13.7 ± 0.736 53.9 ± 9.96 (h*ng/mL) MRT_(0-inf) (h) 1.53 (n = 1) 2.04 (n = 2)  2.39 ± 0.236  1.42 ± 0.356  1.42 ± 0.128  1.20 ± 0.0102

TABLE 53A Summary of mean plasma exposure of psilocin as a function of C(IV) dose. C(IV) dose 0.293 mg/kg 0.275 mg/kg 0.789 mg/kg 2.52 mg/kg Parameter i.v. p.o. p.o. p.o. C_(max/)Dose^(a) 219 ± 248 30.3 ± 9.31 16.4 ± 3.89 20.9 ± 2.17 (kg*ng/mL/mg) Apparent t_(1/2) (h)  1.42 ± 0.253  1.47 ± 0.637  1.43 ± 0.219  1.82 ± 0.291 AUC_(0-tlast)/Dose^(a) 72.4 ± 67.7 26.1 ± 8.26  17.0 ± 0.916 21.2 ± 3.93 (h*kg*ng/mL/mg)

In Vitro Survey of Pharmacological Interaction Profiles at Receptors, Transporters and Enzymes Linked to Targeted Health Conditions.

All assays were performed as described for Example 1, except compound C(IV) was used in place of C(V). To assess assay performance and establish positive control benchmarks, ligands listed in Table 14B were evaluated alongside test derivative. Results for all assays using compound C(IV) or positive controls are shown in Table 53B.

TABLE 53B Data summary table of target assays for compound C(IV) and control ligands. Potency (EC₅₀ or IC₅₀) is provided in units of μM. AGN, agonist; ANT, antagonist; OP, opener; BL, blocker; IN, inhibitor. Target name Target type Assay type EC₅₀ (control) IC₅₀ (control) EC₅₀ (C-IV) IC₅₀ (C-IV) ADRA1A GPCR AGN 5.00E−05 — >100 — ADRA1A GPCR ANT — 9.60E−04 — 26.39 ADRA2A GPCR AGN 4.00E−05 — >100 — ADRA2A GPCR ANT — 3.10E−03 — >100 AVPR1A GPCR AGN 4.20E−04 — >100 — AVPR1A GPCR ANT — 1.60E−03 — >100 CHRM1 GPCR AGN 9.70E−03 — >100 — CHRM1 GPCR ANT — 6.10E−03 — >100 CHRM2 GPCR AGN 2.70E−02 — >100 — CHRM2 GPCR ANT — 3.20E−03 — >100 CNR1 GPCR AGN 1.00E−05 — >100 — CNR1 GPCR ANT — 6.20E−04 — >100 DRD1 GPCR AGN 9.10E−02 — >100 — DRD1 GPCR ANT — 7.10E−04 — 32.89 DRD2S GPCR AGN 5.10E−04 — 1.4 — DRD2S GPCR ANT — 9.60E−04 — >100 HTR1A GPCR AGN 1.70E−03 — 5.56 — HTR1A GPCR ANT — 4.60E−02 — >100 HTR1B GPCR AGN 9.00E−05 — 2.70E−02 — HTR1B GPCR ANT — 5.80E−03 — >100 HTR2B GPCR AGN 6.30E−04 — >100 — HTR2B GPCR ANT — 4.00E−04 — 5.90E−02 OPRD1 GPCR AGN 5.00E−05 — 37.84 — OPRD1 GPCR ANT — 5.80E−04 — >100 GABAA Ion channel OP 6.2 — >100 — GABAA Ion channel BL — 4.6 — >100 HTR3A Ion channel OP 3.00E−01 — >100 — HTR3A Ion channel BL — 1.90E−03 — 76.66 MAO-A Enzyme IN — 2.90E−03 — 34.36 DAT transporter BL — 1.40E−03 — >100 NET transporter BL — 6.70E−03 — >100 SERT transporter BL — 1.80E−03 — 67.95 NMDAR Ion channel BL — 8.00E−02 — >100 NMDAR Ion channel OP 4.40E−01 — >100 — 

1. A method of synthesizing a chemical compound having chemical formula (I):

wherein R₄ is a carboxylic acid moiety or a derivative thereof, wherein the carboxylic acid moiety or derivative thereof has the chemical formula (II):

wherein the method involves: reacting a chemical compound having chemical formula (III):

with an acyl chloride having the chemical formula (IV):

under reaction conditions sufficient to form the compound having chemical formula (I), wherein in chemical formula (II) and chemical formula (IV) R_(4a) are identical and R_(4a) is an aryl group, a substituted aryl group, a heteroaryl group, a substituted heteroaryl group, an alkyl group, a substituted alkyl group, an amine group, or a substituted amine group, and wherein in chemical formula (I) and chemical formula (III) R_(3a) are identical, R_(3b) are identical, and R_(3a) and R_(3b) are each independently a hydrogen atom, an alkyl group, or aryl group.
 2. A method according to claim 1, wherein the compound having chemical formula (III) and the compound having chemical formula (IV) are reacted in the presence of a base.
 3. A method according to claim 2, wherein the base is triethylamine (Et₃N) or N,N-diisopropylethylamine (DIPEA).
 4. A method according to claim 1, wherein the aryl group and substituted aryl group are a phenyl group and a substituted phenyl group, respectively.
 5. A method according to claim 4, wherein the substituted phenyl group is selected from (i) a halo-substituted phenyl group, and optionally a per-fluorinated phenyl, (ii) a trifluoromethylated phenyl group (—CF₃), (iii) a trifluoromethoxy phenyl group (—OCF₃), (iv) a phenyl group in which two substituents on the phenyl group are joined together to form an additional 5-7-membered carbocyclic or heterocyclic ring, and (v) a phenyl group substituted with an alkoxy group, a substituted alkoxy group, an acetamidyl group or an alkoxycarbonyl group, wherein the alkoxycarbonyl group is optionally a methoxycarbonyl (CH₃OC(═O)—), or a substituted heteroaryl-carbonyl group (heteroaryl-O—C(═O)—).
 6. A method according to claim 1, wherein the alkyl group is a C₁-C₁₀alkyl group, in which optionally, at least one carbon atom in the alkyl chain is replaced with an oxygen (O) atom.
 7. A method according to claim 1, wherein the substituted alkyl group is a C₁-C₁₀ alkyl group, wherein the optional substituents are at least one of halo, C₃-C₆ cycloalkyl, or amino (NH₂).
 8. A method according to claim 5, wherein the 5-7-membered ring is a methylene-dioxy ring, an ethylene-dioxy ring, or a dihydrofuryl ring.
 9. A method according to claim 5, wherein R_(4a) is a substituted pyridine group, and optionally an O-alkylated pyridine group, an O-arylated pyridine group, or a halogenated pyridine group.
 10. A method according to claim 1, wherein the compound having chemical formula (I) is a compound having chemical formula C(V):

the compound having formula (III) is a compound having chemical formula A(I):

and the compound having formula (IV) is a compound having chemical formula B(I):


11. A method according to claim 10, wherein the compound having chemical formula A(I) and the compound having chemical formula B(I) are reacted in the presence of a base selected from triethylamine (Et₃N) and N,N-diisopropylethylamine (DIPEA).
 12. A method according to claim 1, wherein the compound having chemical formula (I) is a compound having chemical formula C(IV):

the compound having formula (III) is a compound having chemical formula A(I):

and the compound having formula (IV) is a compound having chemical formula B(II):


13. A method according to claim 12, wherein the compound having chemical formula A(I) and the compound having chemical formula B(II) are reacted in the presence of a base selected from triethylamine (Et₃N) and N,N-diisopropylethylamine (DIPEA).
 14. A method according to claim 1, wherein the compound having chemical formula (I) is a compound having chemical formula C(VI):

the compound having formula (III) is a compound having chemical formula A(I):

and the compound having formula (IV) is a compound having chemical formula B(III):


15. A method according to claim 14, wherein the compound having chemical formula A(I) and the compound having chemical formula B(III) are reacted in the presence of a base selected from triethylamine (Et₃N) and N,N-diisopropylethylamine (DIPEA).
 16. A method according to claim 1, wherein the compound having chemical formula (I) is a compound having formula C(VII):

the compound having formula (III) is a compound having chemical formula A(I):

and the compound having formula (IV) is a compound having chemical formula B(IV):


17. A method according to claim 16, wherein the compound having chemical formula A(I) and the compound having chemical formula B(IV) are reacted in the presence of a base selected from triethylamine (Et₃N) and N,N-diisopropylethylamine (DIPEA).
 18. A method according to claim 1, wherein the compound having chemical formula (I) is a compound having formula C(III):

the compound having formula (III) is a compound having chemical formula A(I):

and the compound having formula (IV) is a compound having chemical formula B(V):


19. A method according to claim 18, wherein the compound having chemical formula A(I) and the compound having chemical formula B(V) are reacted in the presence of a base selected from triethylamine (Et₃N) and N,N-diisopropylethylamine (DIPEA).
 20. A method according to claim 1, wherein the compound having chemical formula (I) is a compound having formula C(XLIII):

the compound having formula (III) is a compound having chemical formula A(I):

and the compound having formula (IV) is a compound having chemical formula B(VI):


21. A method according to claim 20, wherein the compound having chemical formula A(I) and the compound having chemical formula B(VI) are reacted in the presence of a base selected from triethylamine (Et₃N) and N,N-diisopropylethylamine (DIPEA).
 22. A method according to claim 1, wherein the compound having chemical formula (I) is a compound having formula C(I):

the compound having formula (III) is a compound having chemical formula A(I):

and the compound having formula (IV) is a compound having chemical formula B(VII):


23. A method according to claim 22, wherein the compound having chemical formula A(I) and the compound having chemical formula B(VII) are reacted in the presence of a base selected from triethylamine (Et₃N) and N,N-diisopropylethylamine (DIPEA).
 24. A method according to claim 1, wherein the compound having chemical formula (I) is a compound having formula C(XX):

the compound having formula (III) is a compound having chemical formula A(I):

and the compound having formula (IV) is a compound having chemical formula B(VIII):


25. A method according to claim 24, wherein the compound having chemical formula A(I) and the compound having chemical formula B(VII) are reacted in the presence of a base selected from triethylamine (Et₃N) and N,N-diisopropylethylamine (DIPEA). 